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amavisd-milter(8)

NAME

amavisd-milter - sendmail milter for amavis

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]

DESCRIPTION

The amavisd-milter is a sendmail milter (mail filter) for amavis 2.4.3 and above and sendmail 8.13 and above.

With the amavisd-milter, a full amavis functionality is available, including adding spam and virus information header fields, modifying the Subject, adding address extensions and removing certain recipients from delivery, while delivering the same message to the rest.

For more information you can visit amavisd-milter website:

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

Options

The options are as follows:

-B : Uses the milter macro {daemon_name} as the policy bank name (see POLICY BANKS below).

-d debug-level : Set the debug level. The debugging traces become more detailed as the debug level increases. Maximum is 9.

-D delivery-care-of : Set AM.PDP request attribute delivery_care_of to client (default) or server.

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

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. $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). Print debugging messages to the terminal.

-h : Print the help page and exit.

-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.

-M timeout : Timeout for message processing in seconds (default 300 seconds = 5 minutes). Must be less then timeout for a response to the final "." that terminates a message on 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), the timeout must be sufficient to process message in all milters.

-p pidfile : Use this pid file.

-P : When the amavis fails, the message will be passed through unchecked.

-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 : Communication socket between sendmail and amavisd-milter. The protocol spoken over this socket is MILTER (Mail FILTER). It must have the same vale 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 : 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 vale 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), the timeout must be sufficient to process message in all milters.

-T timeout : Amavis connection timeout in seconds (default 600 = 10 minutes). Must be sufficient to process message in amavis. Usually, it is a good idea to set them to the same value as sendmail connection timeout.

-v : Report the version number and exit.

-w directory : Set 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 name of the MTA.

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

SMTP_AUTH : 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 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 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.

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 on 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

AUTHORS

This manual page was written by Petr Rehor and is based on Jerzy Sakol initial work.

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.

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.