IMAPSYNC(1)

📦

version 2.314 · 5 versions

💖 NAME 💖

imapsync — the email tool for syncing two IMAP accounts, one way, and without duplicates. This is the imapsync manual page, user-contributed Perl documentation, and honestly it’s giving “your mailboxes are getting a glow-up” energy. 💌

🌸 VERSION 🌸

This documentation refers to Imapsync $Revision: 2.314 $ ✨

✨ USAGE ✨

Okay bestie, to synchronize the source imap account "test1" on server "test1.lamiral.info" with password "secret1" to the destination imap account "test2" on server "test2.lamiral.info" with password "secret2", do this exact thing:

imapsync \
 --host1 test1.lamiral.info --user1 test1 --password1 secret1 \
 --host2 test2.lamiral.info --user2 test2 --password2 secret2

🦋 DESCRIPTION 🦋

Sometimes we need to transfer mailboxes from one imap server to another. That’s the plot. 📬

The imapsync command is a tool allowing incremental and recursive imap transfers from one mailbox to another. If you don’t understand the previous sentence, it’s normal; it’s pedantic computer-oriented jargon. No cap.

All folders are transferred, recursively, meaning the whole folder hierarchy is taken, all sub-folders, all messages in them, and all message flags (\Seen, \Answered, \Flagged, etc.) are synced too. The way that whole tree gets carried over is honestly iconic. 🌳✨

Imapsync reduces the amount of data transferred by not transferring a given message if it already resides on the destination side. Messages that are on the destination side but not on the source side stay as they are. There is no deletions by default. See the --delete2 option to have strict sync and delete them.

How does imapsync know a message is already on both sides? Same specific headers, and the transfer is done only once. By default, the identification headers are Message-Id: and Received: lines. This choice can be changed with the --useheader option. Most often, a duplicate problem is solved by using --useheader "Message-Id".

All flags are preserved, unread messages will stay unread, read ones will stay read, and deleted ones will stay deleted. 💅

Flags are also resynchronized at each run, unless the option --noresyncflags is used.

A point about message deletions. In the IMAP protocol, a deleted message is not deleted, it is marked \Deleted and can be undeleted. Real destruction comes with the EXPUNGE or UIDEXPUNGE IMAP commands. 💀

You can abort the transfer at any time and restart it later. Imapsync works well with bad connections and interruptions, by design. On a terminal, hit Ctrl+c (Ctrl-c) twice within two seconds to abort the program. Hit Ctrl+c just once to make imapsync reconnect to both imap servers.

How do you know the sync is finished and well done? When imapsync ends by itself, it mentions it with lines like those:

Exiting with return value 0 (EX_OK: successful termination) 0/50 nb_errors/max_errors PID 20332
Removing pidfile /home/gilles/tmp/imapsync.pid
Log file is LOG_imapsync/2023_08_21_11_51_27_651_test1_test2.txt ( to change it, use --logfile filepath ; or use --nolog to turn off logging )

If you don’t have those lines, it means that either the sync process is still running (or eventually hanging indefinitely) or that it ended without a whisper, a strong kill -9 on Linux, for example.

If you have those final lines, then it means the sync process is properly finished. It may have encountered problems, though.

A good synchronization is mentioned by some lines above the last ones, especially those three lines:

The sync looks good, all 1745 identified messages in host1 are on host2.
There is no unidentified message on host1.
Detected 0 errors

Imapsync mentions the total sizes of both accounts at the beginning of the sync and also at the end. Sometimes, even with a strict sync, those total sizes differ, and sometimes they differ a lot. The difference is not a good criterion to conclude the sync went wrong. 🫶

Why? That’s because message sizes given by the imap servers are not always accurate; they are not always the same as the actual message sizes of the messages transferred by imapsync. Imapsync uses the sizes given by the imap servers to calculate the total size. They can differ. In the early days, Imapsync used the sizes of the messages as one of the criteria to identify the messages; different sizes implied different messages. But it was a mistake, the same message had different sizes on both sides sometimes, depending on the imap servers.

Another explanation for a big total size difference is that Gmail doesn’t count the size of duplicate messages across folders twice, while imapsync does.

A classical scenario is synchronizing a mailbox B from another mailbox A, where you just want to keep a strict copy of A in B. Strict means that all messages in A will be in B but no more.

For a strict synchronization, use the option --delete2. The option --delete2 deletes the messages in the host2 folder B that are not in the host1 folder A. If you also need to destroy host2 folders that are not in host1, then use --delete2folders. See also --delete2foldersonly and --delete2foldersbutnot to set up exceptions on folders to destroy. INBOX will never be destroyed; it’s a mandatory folder in IMAP, so imapsync doesn’t even try to remove it. 🚫📥

A different scenario is to delete the messages from the source mailbox after a successful transfer, it can be a good feature when migrating mailboxes since messages will be only on one side. The source account will only have messages that are not on the destination yet, i.e., messages that arrived after a sync or that failed to be transferred.

In that case, use the --delete1 option. Option --delete1 implies also the option --expunge1, so all messages marked deleted on host1 will be deleted. In the IMAP protocol, deleting a message does not delete it; it marks it with the flag \Deleted, allowing an undelete. Expunging a folder removes, definitively, all the messages marked as \Deleted in this folder.

You can also decide to remove empty folders once all of their messages have been transferred. Add --delete1emptyfolders to obtain this behavior.

Imapsync is not adequate for maintaining two active imap accounts in synchronization when the user plays independently on both sides. Use offlineimap (written by John Goerzen) or mbsync (written by Michael R. Elkins) for a 2 ways synchronization.

💅 OPTIONS 💅

usage: imapsync [options]

The standard options are the six values forming the credentials. Three values on each side are needed to login to the IMAP servers. These six values are a hostname, a username, and a password, twice. 🔐

Here are the conventions used in the following descriptions of the options:

str — means a string
int — means an integer number
flo — means a float number
reg — means a regular expression
cmd — means a command
--dry — Makes imapsync do nothing for real; it just prints what would be done without --dry. It’s the “look but don’t touch” mode, bestie. 👀✨

🔐 OPTIONS/credentials 🔐

--host1 str — Source or "from" imap server. It can be a hostname or an IP address.
--port1 int — Port to connect on host1. Optional since the default port is the well-known port imap/143 or imaps/993. Add --ssl1 if you want an SSL/TLS connection on host1.
--user1 str — User to login on host1.
--password1 str — Password of user1.
--host2 str — "destination" imap server.
--port2 int — Port to connect on host2. Optional since the default port is the well-known port imap/143 or imaps/993. Add --ssl2 if you want an SSL/TLS connection on host2.
--user2 str — User to login on host2.
--password2 str — Password of user2.
--showpasswords — Shows passwords on output instead of "MASKED". Useful to restart a complete run by just reading the command line used in the log, or to debug passwords. It’s not a secure practice at all! 🙈
--passfile1 str — Password file for the user1. It must contain the password on the first line. This option avoids showing the password on the command line like --password1 does.
--passfile2 str — Password file for the user2.

You can also pass the passwords in the environment variables IMAPSYNC_PASSWORD1 and IMAPSYNC_PASSWORD2. If you don’t pass the user1 password via --password1 nor --passfile1 nor $IMAPSYNC_PASSWORD1 then imapsync will prompt you to enter the password on the terminal. Same thing for the user2 password. 🫶

🔒 OPTIONS/encryption 🔒

--nossl1 — Do not use an IMAP over SSL/TLS connection on host1.
--ssl1 — Use an IMAP over SSL/TLS connection on host1. It is imaps. The default port is 993. Used by default, if possible.
--nossl2 — Do not use an IMAP over SSL/TLS connection on host2.
--ssl2 — Use an IMAP over SSL/TLS connection on host2. Same as --ssl1 but for host2.
--notls1 — Do not try a "STARTTLS" SSL/TLS connection on host1.
--tls1 — Use a "STARTTLS" SSL/TLS encryption on host1. The default port is 143. Used by default, after imaps probing failed, and if possible.
--notls2 — Do not use a "STARTTLS" SSL/TLS connection on host2.
--tls2 — Use a STARTTLS SSL/TLS encryption on host2. Same as --tls1 but for host2.
--debugssl int — SSL/TLS debug mode from 0 to 4.
--sslargs1 str — Pass any SSL/TLS parameter for the host1 connection. Example:

--sslargs1 SSL_verify_mode=1 --sslargs1 SSL_version=TLSv1_3

See all possibilities in the new() method of IO::Socket::SSL http://search.cpan.org/perldoc?IO::Socket::SSL#Description_Of_Methods

--sslargs2 str — Pass any SSL/TLS parameter for the host2 connection. Same as --sslargs1 but for host2.

🪪 OPTIONS/authentication 🪪

--authmech1 str — Auth mechanism to use with host1: PLAIN, LOGIN, CRAM-MD5 etc. Use UPPERCASE.
--authmech2 str — Auth mechanism to use with host2. See --authmech1
--authuser1 str — User to auth with on host1 (admin user). Avoid using --authmech1 SOMETHING with --authuser1.
--authuser2 str — User to auth with on host2 (admin user).
--proxyauth1 — Use proxyauth on host1. Requires --authuser1. Required by Sun/iPlanet/Netscape IMAP servers to be able to use an administrative user.
--proxyauth2 — Use proxyauth on host2. Requires --authuser2.
--authmd51 — Use MD5 authentication for host1. 🔐
--authmd52 — Use MD5 authentication for host2. 🔐
--domain1 str — Domain on host1 (NTLM authentication).
--domain2 str — Domain on host2 (NTLM authentication).
--oauthaccesstoken1 str — The access token to authenticate with OAUTH2 on host1. It will be combined with the --user1 value to form the string to pass with XOAUTH2 authentication. Instead of the access token itself, the value can be the file containing the access token on the first line. If the value is a file, imapsync reads its first line and takes this line as the access token. The advantage of the file is that if the access token changes then imapsync can read it again when it needs to reconnect during a run. ✨
--oauthaccesstoken2 str — same thing as --oauthaccesstoken1 but for host2.
--oauthdirect1 str — The direct string to pass with XOAUTH2 authentication for host1.
--oauthdirect2 str — same thing as --oauthdirect1 but for host2.
--oauthrefreshcmd1 str — An optional command to call, to refresh the host1 token before any oauth authentication. It can have arguments like "cmd arg1 arg2 ..."
--oauthrefreshcmd2 str — same thing as --oauthrefreshcmd1 but for host2.

🦋 OPTIONS/folders 🦋

--folder str — Sync this folder. Use it again for more folders, like --folder str and this one, etc.
--folderrec str — Sync this folder and all its sub-folders. Use it again for more, like --folderrec str and this one, etc.
--folderfirst str — Sync this folder first. Ex. --folderfirst "INBOX". Use it again for then this one, etc.
--folderlast str — Sync this folder last. --folderlast "[Gmail]/All Mail". Use it again for then this one, etc.
--nomixfolders — Do not merge folders when host1 is case-sensitive while host2 is not (like Exchange). Only the first similar folder is synced. Example: with folders "Sent", "SENT" and "sent" on host1, only "Sent" will be synced to host2. 💅
--skipemptyfolders — Empty host1 folders are not created on host2.
--include reg — Sync folders matching this regular expression. Use it again for or this one, etc. If both --include --exclude options are used, then include is done before.
--exclude reg — Skips folders matching this regular expression. Several folders to avoid: --exclude 'fold1|fold2|f3' skips fold1, fold2 and f3. Use it again for or this one, etc.
--automap — guesses folder mapping, for folders well known as "Sent", "Junk", "Drafts", "All", "Archive", "Flagged". 🗂️
--f1f2 str1=str2 — Force folder str1 to be synced to str2. --f1f2 overrides --automap and --regextrans2. Use several --f1f2 options to map several folders. Option --f1f2 is a one-to-one-only folder mapping, and str1 and str2 must be full path folder names. Use --regextrans2 for more general mappings.
--subfolder2 str — Syncs the whole host1 folders hierarchy under the host2 folder named str. It does it internally by adding three --regextrans2 options before all others. Add --debug to see what's going on. 🔍
--subfolder1 str — Syncs the host1 folders hierarchy which is under folder str to the root hierarchy of host2. It's the counterpart of a sync done by --subfolder2 when doing it in the reverse order. Backup/Restore scenario: Use --subfolder2 str for a backup to the folder str on host2. Then use --subfolder1 str for restoring from the folder str, after inverting host1/host2 user1/user2 values.
--subscribed — Transfers subscribed folders.
--subscribe — Subscribe to the folders transferred on the host2 that are subscribed on host1. On by default. ✅
--subscribeall — Subscribe to the folders transferred on the host2 even if they are not subscribed on host1.
--prefix1 str — Remove prefix str to all destination folders, usually "INBOX." or "INBOX/" or an empty string "". imapsync guesses the prefix if the host1 imap server does not have NAMESPACE capability. So this option should not be used most of the time.
--prefix2 str — Add prefix to all host2 folders. See --prefix1.
--sep1 str — Host1 separator. This option should not be used most of the time. Imapsync gets the separator from the server itself, by using NAMESPACE, or it tries to guess it from the folder listing (it counts characters /, ., \\, \ in folder names and choose the more frequent, or finally / if nothing is found.
--sep2 str — Host2 separator. See --sep1.
--regextrans2 reg — Apply the whole regex to each destination folder. Use it again for and this one. etc. When you play with the --regextrans2 option, first add also the safe options --dry --justfolders. Then, when happy, remove --dry for a run, then remove --justfolders for the next ones. Have in mind that --regextrans2 is applied after the automatic prefix and separator inversion. For examples see: https://imapsync.lamiral.info/FAQ.d/FAQ.Folders_Mapping.txt 🫶

🌸 OPTIONS/folders sizes 🌸

--nofoldersizes — Do not calculate the size of each folder at the beginning of the sync. The default behaviour calculates them.
--nofoldersizesatend — Do not calculate the size of each folder at the end of the sync. The default behaviour calculates them.
--justfoldersizes — Exit after having printed the initial folder sizes.

🎀 OPTIONS/tmp 🎀

--tmpdir str — Where to store temporary files and subdirectories. Will be created if it doesn't exist. Default is $HOME/tmp. It used to be /tmp on Unix, before imapsync 2.250. But /tmp is not safe, see https://github.com/imapsync/imapsync/issues/399 and https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-34204 ⚠️
--pidfile str — The file where the imapsync pid is written. It can be specified with the form dirname/filename, ie, a complete path. The default name is imapsync.pid in tmpdir.
--pidfilelocking — Abort if pidfile already exists. Useful to avoid concurrent transfers on the same mailbox. 🔒

💜 OPTIONS/log 💜

--nolog — Turn off logging on file. By default in Docker context.
--log — Turn on logging on file. By default in normal and CGI contextes.
--logfile str — Change the default log filename (can be dirname/filename).
--logdir str — Change the default log directory. Default is LOG_imapsync/

The default logfile name is, for example:

LOG_imapsync/2019_12_22_23_57_59_532_user1_user2.txt

where:

2019_12_22_23_57_59_532 is nearly the date of the start in the format YYYY_MM_DD_HH_MM_SS_mmm corresponding to the meaning year_month_day_hour_minute_second_millisecond
and user1 user2 are the --user1 --user2 values.

⭐ OPTIONS/messages ⭐

--skipmess reg — Skips messages matching the regex. Example: 'm/[\x80-\xff]/' # to avoid 8bits messages. --skipmess is applied before --regexmess. Use it again for or this one, etc.
--skipcrossduplicates — Avoid copying messages that are already copied in another folder, good from Gmail to XYZ when XYZ is not also Gmail. Activated with --gmail1 unless --noskipcrossduplicates 🍓
--debugcrossduplicates — Prints which messages (UIDs) are skipped with --skipcrossduplicates and in what other folders they are.
--pipemess cmd — Apply this cmd command to each message content before the copy. Use it again for and this one, etc. With several --pipemess, the output of each cmd command (STDOUT) is given to the input (STDIN) of the next command. For example, --pipemess cmd1 --pipemess cmd2 --pipemess cmd3 is like a Unix pipe: "cat message | cmd1 | cmd2 | cmd3"
--disarmreadreceipts — Disarms read receipts (host2 Exchange issue)
--regexmess reg — Apply the whole regex to each message before transfer. Example: 's/\000/ /g' # to replace null characters by spaces. Use it again for and this one, etc.
--truncmess int — truncates messages when their size exceeds the int value, specified in bytes. Good to sync too big messages or to "suppress" attachments. Have in mind that this way, messages become uncoherent somehow. 😭
--nodry1 — makes imapsync fetching messages from host1, even when --dry is on. --dry --nodry1 is useful when debugging transformation options like --pipemess or --regexmess

🧚 OPTIONS/labels 🧚

Gmail presents labels as folders in imap. Imapsync can accelerate the sync by syncing X-GM-LABELS; it will avoid to transferring messages when they are already on host2 in another folder. 👑

--synclabels — Syncs also Gmail labels when a message is copied to host2. Activated by default with --gmail1 --gmail2 unless --nosynclabels is added.
--resynclabels — resyncs Gmail labels when a message is already chilling on host2. It's activated by default with --gmail1 --gmail2 unless you throw in --noresynclabels to opt out 🏷️

For Gmail syncs, see also: https://imapsync.lamiral.info/FAQ.d/FAQ.Gmail.txt

✨ OPTIONS/flags ✨

If you encounter flag problems, see also: https://imapsync.lamiral.info/FAQ.d/FAQ.Flags.txt

--regexflag reg — applies the whole regex to each flags list. Example: 's/"Junk"//g' # to remove "Junk" flag. And you can stack it: --regexflag reg then this one, etc. 🔁
--resyncflags — resyncs flags for messages that were already transferred. On by default, bestie.
--noresyncflags — do NOT resync flags for already-transferred messages. Genuinely useful when a user has already started to play with their host2 account 🫶
--filterbuggyflags — filters out flags that are known to be buggy and generators of errors "BAD Invalid system flag" or "NO APPEND Invalid flag list". iykyk 💅

💀 OPTIONS/deletions 💀

--delete1 — deletes messages on host1 server after a successful transfer. Here's the whole behavior, no cap: it marks messages with the IMAP flag \Deleted, then the messages are deleted with an EXPUNGE IMAP command. If expunging after each message slows down the sync too much, then use --noexpungeaftereach to speed up — expunging will then be done only twice per folder, one at the beginning and one at the end of a folder sync.
--expunge1 — expunges messages on host1 just before syncing a folder. Expunge is done per folder. Expunge aims to really delete messages marked \Deleted. An expunge is also done after each message is copied if option --delete1 is set (unless --noexpungeaftereach).
--noexpunge1 — do not expunge messages on host1.
--delete1emptyfolders — deletes empty folders on host1, INBOX excepted. Useful with --delete1 since what remains on host1 is only what failed to be synced 👑
--delete2 — delete messages in the host2 account that are not in the host1 account. Useful for backup or pre-sync. Oh and heads up: --delete2 implies --uidexpunge2.
--delete2duplicates — deletes messages in host2 that are duplicates in host2. Works only without --useuid since duplicates are detected with a header part of each message. NB: --delete2duplicates is far less violent than --delete2 since it removes only duplicates 🕊️
--delete2folders — delete folders in host2 that are not in host1. Only the selected folders are considered; all folders by default but not all with --exclude --include --folder etc. For safety, first try it like this, it is safe:

--delete2folders --dry --justfolders --nofoldersizes

and see what folders will be deleted. Please actually do this, bestie, I'm begging 😭

--delete2foldersonly reg — delete only folders matching the regex reg. Example: --delete2foldersonly "/^Junk$|^INBOX.Junk$/". This option activates --delete2folders.
--delete2foldersbutnot reg — do not delete folders matching the regex rex. Example: --delete2foldersbutnot "/Tasks$|Contacts$|Foo$/". This option activates --delete2folders.
--noexpunge2 — do not expunge messages on host2.
--nouidexpunge2 — do not uidexpunge messages on the host2 account that are not on the host1 account.

🎀 OPTIONS/dates 🎀

If you encounter problems with dates, see also: https://imapsync.lamiral.info/FAQ.d/FAQ.Dates.txt

--syncinternaldates — sets the internal dates on host2 as the same as host1. Turned on by default ✨ The internal date is the date when a message arrives on a host (Unix mtime usually).
--idatefromheader — sets the internal dates on host2 to the same as the ones in "Date:" headers.

🦋 OPTIONS/message selection 🦋

--maxsize int — skip messages larger (or equal) than int bytes
--minsize int — skip messages smaller (or equal) than int bytes
--maxage int — skip messages older than int days. The final stats (skipped) don't count the older messages. See also --minage.
--minage int — skip messages newer than int days. The final stats (skipped) don't count newer messages. Here's the whole vibe, and + zone are the messages selected:

past|----maxage+++++++++++++++>now
past|+++++++++++++++minage---->now
past|----maxage+++++minage---->now (intersection)
past|++++minage-----maxage++++>now (union, magic!)

--search str — selects only messages returned by this IMAP SEARCH command. Applied on both sides. For a complete set of what can be searched, see https://imapsync.lamiral.info/FAQ.d/FAQ.Messages_Selection.txt
--search1 str — same as --search but for selecting host1 messages only.
--search2 str — same as --search but for selecting host2 messages only. So --search CRIT equals --search1 CRIT --search2 CRIT
--noabletosearch — makes --minage and --maxage options use the internal dates given by a FETCH imap command instead of the "Date:" header. The internal date is the arrival date in the mailbox. --noabletosearch equals --noabletosearch1 --noabletosearch2
--noabletosearch1 — like --noabletosearch but for host1 only.
--noabletosearch2 — like --noabletosearch but for host2 only.
--maxlinelength int — skip messages with a line length longer than int bytes. RFC 2822 says it must be no more than 1000 bytes, but real-life servers and email clients do much more 🙈
--useheader str — use this header to compare messages on both sides. Example: "Message-Id" or "Received" or "Date". And you can stack it: --useheader str and this one, etc.
--syncduplicates — sync also duplicates. Off by default.
--usecache — use cache to speed up next syncs. Off by default.
--nousecache — do not use cache. Caveat: --useuid --nousecache creates duplicates on multiple runs 💀
--useuid — use UIDs instead of headers as a criterion to recognize messages. Option --usecache is then implied unless --nousecache is used.

🌸 OPTIONS/miscellaneous 🌸

--syncacls — synchronizes ACLs (Access Control Lists). Lowkey be careful though: ACLs in IMAP are not standardized, since one ACL code on one side may signify something else on the other side.
--nosyncacls — does not synchronize ACLs. This is the default.
--addheader — when a message has no headers to be identified, --addheader adds a "Message-Id" header, like "Message-Id: 12345@imapsync", where 12345 is the imap UID of the message on the host1 folder. Useful to sync folders "Sent" or "Draft" 📨

🔍 OPTIONS/debugging 🔍

--debug — show debug notes.
--debugfolders — show debug notes for the folders part only.
--debugcontent — show content of the messages transferred. Huge output. Like, huge huge 🫠
--debugflags — show debug notes for flags.
--debugimap1 — show IMAP notes for host1. Very verbose.
--debugimap2 — show IMAP notes for host2. Very verbose.
--debugimap — show IMAP notes for host1 and host2. Twice very verbose 😭
--debugmemory — show the memory consumption after each copy.
--errorsmax int — exit when int number of errors is reached. The default is 50 errors to quit.
--tests — run local non-regression tests. Exit code 0 means everything is ok ✨
--testslive — run a live test with test1.lamiral.info imap server. Useful to check the basics. It needs an internet connection.
--testslive6 — run a live test with tests1ipv6.lamiral.info imap server. Useful to check the IPv6 connectivity. Needs internet.

🎯 OPTIONS/specific 🎯

--gmail1 — sets --host1 to Gmail and other options. See FAQ.Gmail.txt
--gmail2 — sets --host2 to Gmail and other options. See FAQ.Gmail.txt
--office1 — sets --host1 to Office365 and other options. See FAQ.Office365.txt
--office2 — sets --host2 to Office365 and other options. See FAQ.Office365.txt
--exchange1 — sets options for Exchange. See FAQ.Exchange.txt
--exchange2 — sets options for Exchange. See FAQ.Exchange.txt
--domino1 — sets options for Domino. See FAQ.Domino.txt
--domino2 — sets options for Domino. See FAQ.Domino.txt

⏱️ OPTIONS/behavior ⏱️

--timeout1 flo — connection timeout in seconds for host1. Default is 120 and 0 means no timeout at all.
--timeout2 flo — connection timeout in seconds for host2. Default is 120 and 0 means no timeout at all.

Caveat emptor. Under CGI context, you may encounter a timeout from the web server, killing imapsync and the imap connections. See the document INSTALL.OnlineUI.txt and search for "Timeout" for how to deal with this issue.

--keepalive1 — https://metacpan.org/pod/Mail::IMAPClient#Keepalive. Some firewalls and network gears like to timeout connections prematurely if the connection sits idle. This option enables SO_KEEPALIVE on the host1 socket. --keepalive1 is on by default since imapsync release 2.169. Use --nokeepalive1 to disable it.
--keepalive2 — same as --keepalive2 but for host2. Use --nokeepalive2 to disable it.
--maxmessagespersecond flo — limits the average number of messages transferred per second. 🚦
--maxbytespersecond int — caps the average transfer rate per second, bestie. Chill speeds only 💅
--maxbytesafter int — the --maxbytespersecond limit doesn't kick in until after int bytes have already been moved. Like, warm-up era ✨
--maxsleep flo — never sleep more than int seconds (yes, the flag says flo, the description says int, we don't make the rules). It's on by default at 2 seconds max, literally the same as --maxsleep 2 😴
--abort — kills a previous imapsync call that's still running. It finds the target via the pidfile, so it knows exactly which process to end 🔪
--exitwhenover int — stops syncing and exits once int total bytes have been transferred. Bye at the byte limit 👋
--version — prints only the software version. Nothing else, just the number 🎀
--noreleasecheck — no checking for a new imapsync release 🙅
--releasecheck — checks for a new imapsync release. It's an HTTP GET request to http://imapsync.lamiral.info/prj/imapsync/VERSION 📡
--emailreport1 — drops the final email report into host1's INBOX 📬
--emailreport2 — drops the final email report into host2's INBOX 📬
--noemailreport1 — does not put the final email report in host1's INBOX 🚫
--noemailreport2 — does not put the final email report in host2's INBOX 🚫
--noid — don't send or receive the IMAP "ID" command to the imap servers. Skipping the small talk 🫥
--justconnect — just connects to both servers and prints useful info. Only needs the --host1 and --host2 options. Obsolete since imapsync --host1 imaphost on its own already implies --justconnect 👑
--justlogin — just logs into both host1 and host2 with the users' credentials, then dips out 🚪
--justfolders — does only folder things, ignores messages entirely. Folder admin main character energy 📁
--help — prints this help, bestie 🥰

Example time, because examples ate: to sync the IMAP account "test1" on "test1.lamiral.info" over to the imap account "test2" on "test2.lamiral.info", with the test1 account password being "secret1" and the test2 account password being "secret2":

imapsync \
   --host1 test1.lamiral.info --user1 test1 --password1 secret1 \
   --host2 test2.lamiral.info --user2 test2 --password2 secret2

🔒 SECURITY 🔒

Use --passfile1 instead of --password1 to give the password, because it's safer, periodt. With the --password1 option, on Linux, literally any user on your host can see that password by running 'ps auxwwww' 😭 Using a variable (like IMAPSYNC_PASSWORD1) is also dangerous, thanks to the 'ps auxwwwwe' command. So the move is: save the password in a well-protected file (600 or rw-------) and that's the best solution, no cap 🛡️

Imapsync activates SSL/TLS encryption by default, if possible.

But what detailed behavior is under this "if possible"? Let's get into it 🧐

Imapsync activates the SSL/TLS mechanism if the well-known imaps port (993) is open on the imap servers. If the imaps port is closed, then imapsync opens a normal (clear) connection on port 143. But then it looks for STARTTLS support in the CAPABILITY list of the servers. If STARTTLS is supported, then imapsync goes to an SSL/TLS encryption with the STARTTLS IMAP command. Slay ✨

If the automatic SSL/TLS detections fail, then imapsync uses clear-text communication. And clear-text communication does not protect against sniffing activities on the network, especially passwords. That's a real one, be careful 💀

If you want to force SSL/TLS, just use --ssl1, --ssl2 or --tls1 --tls2. Imapsync won't go to clear-text communication with any of these options 🔐

See also the document FAQ.Security.txt in the FAQ.d/ directory or at https://imapsync.lamiral.info/FAQ.d/FAQ.Security.txt

🚪 EXIT STATUS 🚪

Imapsync will exit with a 0 status (return code) if everything goes well. Otherwise, it exits with a non-zero status. That's classical Unix behavior, iykyk. Here's the list of the exit code values (an integer between 0 and 255). In Bourne Shells, this exit code value can be retrieved within the variable value "$?" if you read it just after the imapsync call 👀

The names reflect their meaning:

EX_OK          => 0  ; #/* successful termination */
EX_USAGE       => 64 ; #/* command line usage error */
EX_NOINPUT     => 66 ; #/* cannot open input */
EX_UNAVAILABLE => 69 ; #/* service unavailable */
EX_SOFTWARE    => 70 ; #/* internal software error */
EXIT_CATCH_ALL              =>   1 ; # Any other error
EXIT_BY_SIGNAL              =>   6 ; # Should be 128+n where n is the sig_num
EXIT_BY_FILE                =>   7 ;
EXIT_PID_FILE_ERROR         =>   8 ;
EXIT_CONNECTION_FAILURE     =>  10 ;
EXIT_TLS_FAILURE            =>  12 ;
EXIT_AUTHENTICATION_FAILURE =>  16 ;
EXIT_SUBFOLDER1_NO_EXISTS   =>  21 ;
EXIT_WITH_ERRORS            => 111 ;
EXIT_WITH_ERRORS_MAX        => 112 ;
EXIT_OVERQUOTA              => 113 ;
EXIT_ERR_APPEND             => 114 ;
EXIT_ERR_FETCH              => 115 ;
EXIT_ERR_CREATE             => 116 ;
EXIT_ERR_SELECT             => 117 ;
EXIT_TRANSFER_EXCEEDED      => 118 ;
EXIT_ERR_APPEND_VIRUS       => 119 ;
EXIT_ERR_FLAGS              => 120 ;
EXIT_ERR_SEARCH             => 121 ;
EXIT_TESTS_FAILED           => 254 ; # Like Test::More API
EXIT_CONNECTION_FAILURE_HOST1     =>  101 ;
EXIT_CONNECTION_FAILURE_HOST2     =>  102 ;
EXIT_AUTHENTICATION_FAILURE_USER1 =>  161 ;
EXIT_AUTHENTICATION_FAILURE_USER2 =>  162 ;

📜 LICENSE AND COPYRIGHT 📜

Imapsync is a free, open, and public but not always gratis software tool covered by the NOLIMIT Public License, now called NLPL. See the LICENSE file included in the distribution, or just read the following simple sentence as it IS the license text:

"No limits to do anything with this work and this license."

In case it is not long enough, I repeat:

"No limits to do anything with this work and this license."

Look at https://imapsync.lamiral.info/LICENSE 👑

👑 AUTHOR 👑

Gilles LAMIRAL <gilles@lamiral.info>

Good feedback is always welcome. Bad feedback is very often welcome. FR FR 🫶

Gilles LAMIRAL earns his living by writing, installing, configuring, and sometimes teaching free, open, and often gratis software. Imapsync used to be always gratis, but now it is only often gratis. It's because imapsync is sold by its author, your servitor, a good way to maintain and support free open public software tools over decades. Respect the hustle 💖

🐛 BUGS AND LIMITATIONS 🐛

See https://imapsync.lamiral.info/FAQ.d/FAQ.Reporting_Bugs.txt

🖥️ IMAP SERVERS supported 🖥️

See https://imapsync.lamiral.info/S/imapservers.shtml

🚛 HUGE MIGRATION 🚛

If you have many mailboxes to migrate, think about a little shell program. Write a file called file.txt (for example) containing users and passwords. The separator used in this example is ';' ✨

The file.txt file contains:

user001_1;password001_1;user001_2;password001_2
user002_1;password002_1;user002_2;password002_2
user003_1;password003_1;user003_2;password003_2
user004_1;password004_1;user004_2;password004_2
user005_1;password005_1;user005_2;password005_2 ...

On Unix, the shell program can be:

{ while IFS=';' read  u1 p1 u2 p2; do
       imapsync --host1 imap.side1.org --user1 "$u1" --password1 "$p1" \
                --host2 imap.side2.org --user2 "$u2" --password2 "$p2" ...
done ; } < file.txt

On Windows, the batch program can be:

FOR /F "tokens=1,2,3,4 delims=; eol=#" %%G IN (file.txt) DO imapsync ^
--host1 imap.side1.org --user1 %%G --password1 %%H ^
--host2 imap.side2.org --user2 %%I --password2 %%J ...

The ... have to be replaced by nothing or any imapsync option. Welcome to shell or batch programming! 🎉

You will find already written scripts at https://imapsync.lamiral.info/examples/

📦 INSTALL 📦

Imapsync works under any Unix with Perl.

Imapsync works under most Windows (2000, XP, Vista, Seven, Eight, Ten, Eleven, and all Server releases 2000, 2003, 2008 and R2, 2012 and R2, 2016) as a standalone binary software called imapsync.exe, usually launched from a batch file to avoid always typing the options. See https://imapsync.lamiral.info/README_Windows.txt 🪟

Imapsync works under OS X as a standalone binary software called imapsync_bin_Darwin See https://imapsync.lamiral.info/INSTALL.d/INSTALL.Darwin.txt 🍎

Purchase the latest imapsync at https://imapsync.lamiral.info/ 🛒

You'll receive a link to a compressed tarball called imapsync-2.xxx.tgz, where 2.xxx is the version number. Untar the tarball where you want (on Unix):

tar xzvf  imapsync-2.xxx.tgz

Go into the directory imapsync-x.xx and read the INSTALL file. As mentioned at https://imapsync.lamiral.info/#install, the INSTALL file can also be found at https://imapsync.lamiral.info/INSTALL.d/INSTALL.ANY.txt It is now split into several files for each system https://imapsync.lamiral.info/INSTALL.d/ 📂

⚙️ CONFIGURATION ⚙️

There is no specific configuration file for imapsync; everything is specified by the command line parameters and the default behavior. Command line girlies rise 🎀

🛠️ HACKING 🛠️

Feel free to hack imapsync as the NOLIMIT license permits it. Go off bestie 💅

👯 SIMILAR SOFTWARE 👯

See https://imapsync.lamiral.info/S/external.shtml

🕰️ HISTORY 🕰️

I initially wrote imapsync in July 2001 because an enterprise, called BaSystemes, paid me to install a new imap server without losing huge old mailboxes located in a far-away remote imap server, accessible by an often broken low-bandwidth ISDN link. The lore is real 📖

I had to verify every mailbox was well transferred, all folders, and all messages, without wasting bandwidth or creating duplicates upon resyncs. The imapsync design was made with the beautiful rsync command in mind. Iconic behavior honestly ✨

Imapsync originated as a patch to the copy_folder.pl script. The script copy_folder.pl comes from the Mail-IMAPClient-2.1.3 perl module tarball source (more precisely, in the examples/ directory of the Mail-IMAPClient tarball). Origin story unlocked 🔓

So many changes have happened since then that I wonder if any lines of the original copy_folder.pl in the imapsync source code remain. Glow-up of the century 💖

And that's the whole page, bestie — wrote by perl v5.42.0, dated 2025-09-28, and it's IMAPSYNC(1) all the way through 🦋🌸 Go forth and migrate those mailboxes 💜

📦 where this page comes from

arch rolling: imapsync 2.314-1 · custom:imapsync
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-06: a language model's rewrite of the original, under its terms