amavisd-milter(8)

📦
version 1.7.2 · 6 versions
, in alpine 3.22, alpine 3.23, alpine 3.24, arch rolling

💌 amavisd-milter(8) — the sendmail milter for amavis, bestie edition

okay so picture this: it's amavisd-milter(8), a System Manager's Manual page, and it's about to become your new fav thing. sit down, grab a snack 🍓

✨ NAME ✨

amavisd-milter — the sendmail milter for amavis. yes. that's the whole vibe. 🎀

🌸 SYNOPSIS 🌸

amavisd-milter [-Bfhv] [-d debug-level] [-D delivery-care-of] [-m max-
conns] [-M max-wait] [-p pidfile] [-P] [-q backlog] [-s socket]
[-t timeout] [-S socket] [-T timeout] [-w directory]

like, that's it. that's the whole invocation. icons only 💅

💖 DESCRIPTION 💖

So amavisd-milter is a sendmail milter — that's a mail filter, iykyk — built for amavis 2.4.3 and above and sendmail 8.13 and above. no cap.

The way that this slaps is: with amavisd-milter, you get the full amavis functionality, including:

  • adding spam and virus information header fields 🔥
  • modifying the Subject ✏️
  • adding address extensions
  • removing certain recipients from delivery… while still delivering the same message to the rest 🫶

For more info you can literally just go visit the amavisd-milter website:

https://github.com/prehor/amavisd-milter

🦋 OPTIONS 🦋

The options are as follows, bestie — every single one:

  • -B — uses the milter macro {daemon_name} as the policy bank name (peep POLICY BANKS below 👀).
  • -d debug-level — sets the debug level. the higher you go, the more detailed the debugging traces get. maximum is 9. go off 🔍
  • -D delivery-care-of — sets the AM.PDP request attribute delivery_care_of to client (that's the default) or server.

When the client method is used, then amavisd-milter is the one responsible for forwarding the message to the recipients. this method does not allow personalized header or body modification. sorry girl 💀

When the server method is used, then amavis is responsible for forwarding the message to the recipients and may personalize the headers and the body of the messages. heads up: the $forward_method variable in amavisd.conf must point to a place willing to accept the message without further checking in amavis. 💜

  • -f — run amavisd-milter in the foreground (i.e. do not daemonize). prints debugging messages to the terminal. main character energy, no backgrounding 🌈
  • -h — print the help page and exit. short & sweet 🎀
  • -m max-conns — maximum concurrent amavis connections (default 0 = unlimited number of connections). it must be the same as the $max_servers variable in amavisd.conf. fr fr, they gotta match.
  • -M timeout — timeout for message processing in seconds (default 300 seconds = 5 minutes). must be less then the timeout for a response to the final . that terminates a message on the sending MTA. Sendmail uses default value 1 hour, postfix 10 minutes and qmail 20 minutes. recommended value is less than 10 minutes. ⏰

If you use other milters (especially time-consuming ones), the timeout must be sufficient to process the message in all milters. like, all of them. no skipping.

  • -p pidfile — use this pid file. 🗂️
  • -P — when the amavis fails, the message will be passed through unchecked. yes, that's a real thing, and yes, it's a vibe you should think carefully about 🙈
  • -q backlog — sets the incoming socket backlog used by listen(2). if it is not set or set to zero, the operating system default is used.
  • -s socket — the communication socket between sendmail and amavisd-milter. the protocol spoken over this socket is MILTER (Mail FILTER). it must have the same value as the INPUT_MAIL_FILTER macro in sendmail.mc. ⭐

The socket must be in format proto:address:

  • {unix|local}:/path/to/file — a named pipe.
  • inet:port@{hostname|ip-address} — an IPV4 socket.
  • inet6:port@{hostname|ip-address} — an IPV6 socket.
  • -S socket — the communication socket between amavisd-milter and amavis. the protocol spoken over this socket is AM.PDP (AMavis Policy Delegation Protocol). it must have the same value as the $unix_socketname variable in amavisd.conf. 💫

The socket must be in format proto:address:

  • {unix|local}:/path/to/file — a named pipe.
  • inet:port@{hostname|ip-address} — an IPV4 socket.
  • inet6:port@{hostname|ip-address} — an IPV6 socket.
  • -t timeout — sendmail connection timeout in seconds (default 600 = 10 minutes). it must have the same value as the INPUT_MAIL_FILTER macro in sendmail.mc and must be greater than or equal to the amavis connection timeout. 🔗

If you use other milters (especially time-consuming ones), the timeout must be sufficient to process the message in all milters. again. say it with me.

  • -T timeout — amavis connection timeout in seconds (default 600 = 10 minutes). must be sufficient to process the message in amavis. usually, it is a good idea to set them to the same value as the sendmail connection timeout. 👑
  • -v — report the version number and exit. 🏷️
  • -w directory — set the working directory. 📁

👑 POLICY BANKS 👑

If the option -B is enabled, amavisd-milter uses the value of the milter macro {daemon_name} as the name of the amavis policy bank. usually, this milter macro is set to the name of the MTA. cute, right?

When the remote client is authenticated, amavisd-milter uses the authentication information as the name of the amavis policy banks:

  • SMTP_AUTH — the remote client has been authenticated. ✅
  • SMTP_AUTH_<MECH> — the remote client authentication mechanism.
  • SMTP_AUTH_<MECH>_<BITS> — the number of bits used for the key of the symmetric cipher when the authentication mechanism uses it. 🔐

🧚 EXAMPLES 🧚

Configuring amavis

In the amavisd.conf file set protocol and amavis socket to:

$protocol = "AM.PDP";                      # Use AM.PDP protocol
$unix_socketname = "$MYHOME/amavisd.sock"; # Listen on Unix socket
### $inet_socket_port = 10024;             # Do not listen on TCP port

Then (re)start the amavisd daemon. 🚀

Configuring Postfix

Add the following entries to Postfix main.cf*:

smtpd_milters = local:<AMAVISD_MILTER.SOCK>
milter_connect_macros = j {client_name} {daemon_name} v
milter_protocol = 6

Then (re)start the Postfix daemon. ✨

Configuring sendmail

Add the following entries to file sendmail.mc:

define(`confMILTER_MACROS_CONNECT',
  confMILTER_MACROS_CONNECT`, {client_resolve}')
define(`confMILTER_MACROS_ENVFROM',
  confMILTER_MACROS_ENVFROM`, r, b')
INPUT_MAIL_FILTER(`amavisd-milter',
  `S=local:<AMAVISD_MILTER.SOCK>, F=T, T=S:10m;R:10m;E:10m')

Then rebuild the sendmail.cf file, install it and (re)start the sendmail daemon. 🛠️

Running amavisd-milter

This examples assumes that amavis is running as user vscan. the actual name is shown in the $daemon_user variable in amavisd.conf. don't @ me, check your config 💅

Limiting maximum concurrent connections to amavisd

To limit the maximum concurrent connections to amavis, run amavisd-milter with this options:

su - vscan -c "amavisd-milter -m 4"

Troubleshooting

For troubleshooting, run amavisd-milter in the foreground and set the debug level to the appropriate value:

su - vscan -c "amavisd-milter -f -d 4"

Debug levels are:

  • 1 — Not errors but unexpected states (connection abort etc).
  • 2 — Main states in message processing.
  • 3 — All amavisd-milter debug messages.
  • 4-9 — Milter communication debugging (set smfi_setdbg to 1-6). 🔍

🌈 SEE ALSO 🌈


- ```text
https://www.ijs.si/software/amavisd/

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# 💜 AUTHORS 💜

This manual page was written by **Petr Rehor** and is based on **Jerzy Sakol** initial work. give them their flowers 💐

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# 😭 BUGS 😭

Issues can be reported by using GitHub at:

https://github.com/prehor/amavisd-milter/issues


Full detailed information on how to report issues, please see the Contribution Guidelines at:

https://github.com/prehor/amavisd-milter/blob/master/CONTRIBUTING.md


Enhancements, requests and problem reports are welcome. 🫶 we want them, actually.

If you run into problems, first check the GitHub issues before creating a new one. it is very likely that someone has encountered the same problem and it has already been solved. (this is the way.)

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> <rainbow>Version 1.7.2</rainbow> — and that's the whole page, bestie!! `amavisd-milter(8)` said what it said, slayed, and logged off. bye icon 👋💖
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