RFC 2062

Internet Message Access Protocol - Obsolete Syntax ✨

Okay bestie, let's get into RFC 2062 💖 It's called Internet Message Access Protocol - Obsolete Syntax, written by M. Crispin at the University of Washington 🎀 It's Informational, dated December 1996, and it came out of the Network Working Group 🌸 Nothing is listed as obsoleted or updated up top, so there's nothing to chase there ✨

Part 1 of 2 💅

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Status of this Memo 🌸

This memo provides information for the Internet community 💅 It does not specify an Internet standard of any kind, and distribution of this memo is unlimited 🦋

Abstract 💜

So this doc describes obsolete syntax that IMAP4 implementations might bump into when they're dealing with older versions of the Internet Mail Access Protocol 👀 IMAP4 implementations MAY implement this syntax in order to maximize interoperability with older implementations 🫶

It also repeats info from earlier documents, most notably RFC 1176 and RFC 1730 📚

Obsolete Commands and Fetch Data Items 🧚

Okay so these commands are OBSOLETE (yes, all caps, it's serious 😤) It is NOT required to support any of these commands or fetch data items in new server implementations 🙈 They're only documented here for implementors who might want to support them so old client implementations still work 💖

The section headings here line up with where they'd sit in the main document if they weren't obsoleted, so you can still find your way around 🗺️

6.3.OBS.1. FIND ALL.MAILBOXES Command 🌸

Arguments:  mailbox name with possible wildcards

Data:       untagged responses: MAILBOX

Result:     OK - find completed
            NO - find failure: can't list that name
            BAD - command unknown or arguments invalid

The FIND ALL.MAILBOXES command returns a subset of names from the complete set of all names available to the user ✨ It returns zero or more untagged MAILBOX replies 💅 The mailbox argument is similar to the one for LIST with an empty reference, except that the characters % and ? match a single character 🦋

Example:

C: A002 FIND ALL.MAILBOXES *
S: * MAILBOX blurdybloop
S: * MAILBOX INBOX
S: A002 OK FIND ALL.MAILBOXES completed

6.3.OBS.2. FIND MAILBOXES Command 💜

Arguments:  mailbox name with possible wildcards

Data:       untagged responses: MAILBOX

Result:     OK - find completed
            NO - find failure: can't list that name
            BAD - command unknown or arguments invalid

The FIND MAILBOXES command returns a subset of names from the set of names the user has declared as being "active" or "subscribed" 🌈 It returns zero or more untagged MAILBOX replies 🎀 The mailbox argument is similar to the one for LSUB with an empty reference, except that the characters % and ? match a single character 💖

Example:

C: A002 FIND MAILBOXES *
S: * MAILBOX blurdybloop
S: * MAILBOX INBOX
S: A002 OK FIND MAILBOXES completed

6.3.OBS.3. SUBSCRIBE MAILBOX Command 🦋

Arguments:  mailbox name

Data:       no specific data for this command

Result:     OK - subscribe completed
            NO - subscribe failure: can't subscribe to that name
            BAD - command unknown or arguments invalid

The SUBSCRIBE MAILBOX command is identical in effect to the SUBSCRIBE command 🙌 A server that implements this command must be able to distinguish between a SUBSCRIBE MAILBOX command and a SUBSCRIBE command with a mailbox name argument of "MAILBOX" 🤯 That's the whole plot twist, babe 😭

Example:

C: A002 SUBSCRIBE MAILBOX #news.comp.mail.mime
S: A002 OK SUBSCRIBE MAILBOX to #news.comp.mail.mime
completed
C: A003 SUBSCRIBE MAILBOX
S: A003 OK SUBSCRIBE to MAILBOX completed

6.3.OBS.4. UNSUBSCRIBE MAILBOX Command 🥀

Arguments:  mailbox name

Data:       no specific data for this command

Result:     OK - unsubscribe completed
            NO - unsubscribe failure: can't unsubscribe that name
            BAD - command unknown or arguments invalid

The UNSUBSCRIBE MAILBOX command is identical in effect to the UNSUBSCRIBE command 🫠 A server that implements this command must be able to distinguish between an UNSUBSCRIBE MAILBOX command and an UNSUBSCRIBE command with a mailbox name argument of "MAILBOX" 👑 Same energy as the subscribe one, periodt 💅

Example:

C: A002 UNSUBSCRIBE MAILBOX #news.comp.mail.mime
S: A002 OK UNSUBSCRIBE MAILBOX from #news.comp.mail.mime
completed
C: A003 UNSUBSCRIBE MAILBOX
S: A003 OK UNSUBSCRIBE from MAILBOX completed

6.4.OBS.1 PARTIAL Command 🧁

Arguments:  message sequence number
            message data item name
            position of first octet
            number of octets

Data:       untagged responses: FETCH

Result:     OK - partial completed
            NO - partial error: can't fetch that data
            BAD - command unknown or arguments invalid

Okay so PARTIAL is basically FETCH, but with a glow-up: only the number of octets you ask for comes back, starting from the octet you pick 💖 Only a single message can be fetched at a time 🌸 The first octet of a message, and so the minimum starting octet, is octet 1 ✨

The FETCH items that are valid for PARTIAL are RFC822, RFC822.HEADER, RFC822.TEXT, BODY[<section>], plus any .PEEK forms of these 🦋

If a partial fetch tries to read past the end of the text, it gets truncated as appropriate 🫶 And if the starting octet is past the end of the text, you get an empty string back 🫥

The data comes back with the FETCH response, and there's no indication of the range of the partial data in that response 🙈 You also can't stream multiple PARTIAL commands for the same data item without processing and synchronizing at each step, since streamed commands may run out of order 😵‍💫 Not a vibe 💀

There's no requirement that partial fetches follow any sequence 🌈 For example, if a partial fetch of octets 1 through 10000 breaks in an awkward spot for BASE64 decoding, it is permitted to continue with a partial fetch of 9987 through 19987, etc. 🎀 Flexible queen behavior 👑

The handling of the \Seen flag is the same as in the associated FETCH command 💅

Example:

C: A005 PARTIAL 4 RFC822 1 1024
S: * 1 FETCH (RFC822 {1024}
S: Return-Path: <gray@cac.washington.edu>
S: ...
S: .........  FLAGS (\Seen))
S: A005 OK PARTIAL completed

6.4.5.OBS.1 Obsolete FETCH Data Items 🍓

The following FETCH data items are obsolete 🥹

BODY[<...>0]   A body part number of 0 is the [RFC-822] header of
               the message.  BODY[0] is functionally equivalent to
               BODY[HEADER], differing in the syntax of the
               resulting untagged FETCH data (BODY[0] is
               returned).

RFC822.HEADER.LINES <header_list>
               Functionally equivalent to BODY.PEEK[HEADER.LINES
               <header_list>], differing in the syntax of the
               resulting untagged FETCH data (RFC822.HEADER is
               returned).

RFC822.HEADER.LINES.NOT <header_list>
               Functionally equivalent to
               BODY.PEEK[HEADER.LINES.NOT <header_list>],
               differing in the syntax of the resulting untagged
               FETCH data (RFC822.HEADER is returned).

RFC822.PEEK    Functionally equivalent to BODY.PEEK[], except for
               the syntax of the resulting untagged FETCH data
               (RFC822 is returned).

RFC822.TEXT.PEEK
               Functionally equivalent to BODY.PEEK[TEXT], except
               for the syntax of the resulting untagged FETCH data
               (RFC822.TEXT is returned).

Formal Syntax of Obsolete Commands and Responses ✨

okay so here's the grammar bit 💅 every obsolete rule that ends in _old gets tacked onto its buddy in the main formal syntax, like a little accessory 🎀 for example, command_auth_old adds the FIND command to command_auth. iconic, right?

command_auth_old ::= find

command_select_old
                ::= partial

date_year_old   ::= 2digit
                    ;; (year - 1900)

date_time_old   ::= <"> date_day_fixed "-" date_month "-" date_year
                    SPACE time "-" zone_name <">

find            ::= "FIND" SPACE ["ALL."] "MAILBOXES" SPACE
                    list_mailbox

fetch_att_old   ::= "RFC822.HEADER.LINES" [".NOT"] SPACE header_list /
                    fetch_text_old

fetch_text_old  ::= "BODY" [".PEEK"] section_old /
                    "RFC822" [".HEADER" / ".TEXT" [".PEEK"]]

msg_data_old    ::= "COPY" / ("STORE" SPACE msg_att)

partial         ::= "PARTIAL" SPACE nz_number SPACE fetch_text_old SPACE
                    number SPACE number

section_old     ::= "[" (number ["." number]) "]"

subscribe_old   ::= "SUBSCRIBE" SPACE "MAILBOX" SPACE mailbox

unsubscribe_old ::= "UNSUBSCRIBE" SPACE "MAILBOX" SPACE mailbox

zone_name       ::= "UT" / "GMT" / "Z" /                ;; +0000
                    "AST" / "EDT" /                     ;; -0400
                    "EST" / "CDT" /                     ;; -0500
                    "CST" / "MDT" /                     ;; -0600
                    "MST" / "PDT" /                     ;; -0700
                    "PST" / "YDT" /                     ;; -0800
                    "YST" / "HDT" /                     ;; -0900
                    "HST" / "BDT" /                     ;; -1000
                    "BST" /                             ;; -1100
                    "A" / "B" / "C" / "D" / "E" / "F" / ;; +1 to +6
                    "G" / "H" / "I" / "K" / "L" / "M" / ;; +7 to +12
                    "N" / "O" / "P" / "Q" / "R" / "S" / ;; -1 to -6
                    "T" / "U" / "V" / "W" / "X" / "Y"   ;; -7 to -12

Security Considerations 🔐

okay, real talk for a sec 🥺 this memo does not discuss security issues at all. not a single one. so if you're looking for threat models in here, you're gonna be disappointed bestie 💀

Author's Address 🦋

Mark R. Crispin
Networks and Distributed Computing
University of Washington
4545 15th Aveneue NE
Seattle, WA  98105-4527

Phone: (206) 543-5762
EMail: MRC@CAC.Washington.EDU