Rawlog

Dovecot supports logging IMAP/POP3 traffic (also TLS/SSL encrypted). There are several possibilities for this:

rawlog_dir setting (v2.2.26+)
Using rawlog binary, which is executed as post-login script.
Pre-login imap/pop3-login process via -R parameter.

rawlog_dir setting (v2.2.26+)

Dovecot creates *.in and *.out rawlogs to the specified directory if it exists. For example:

protocol imap {
  rawlog_dir = /tmp/rawlog/%u
  # if you want to put files into user's homedir, use this, do not use ~
  #rawlog_dir = %h/rawlog
}

rawlog binary

It works by checking if dovecot.rawlog/ directory exists in the logged in user's home directory, and writing the traffic to yyyymmdd-HHMMSS-pid.in and .out files. Each connection gets their own in/out files. Rawlog will simply skip users who don't have the dovecot.rawlog/ directory and the performance impact for those users is minimal.

Home directory

Note that for rawlog to work, your userdb must have returned a home directory for the user. IMPORTANT: The home directory must be returned by userdb, mail_home setting won't work. Verify that doveadm user -u user@example.com (with -u parameter) returns the home directory, for example:

% doveadm user -u user@example.com
userdb: user@example.com
  user      : user@example.com
  uid       : 1000
  gid       : 1000
  home      : /home/user@example.com

In above configuration rawlog would expect to find /home/user@example.com/dovecot.rawlog/ directory writable by uid 1000.

If your userdb can't return a home directory directly, with v2.1+ you can add:

userdb {
  # ...
  default_fields = home=/home/%u
  # or temporarily even e.g. default_fields = home=/tmp/temp-home
}

You can also set DEBUG environment to have rawlog log an info message why it's not doing anything:

import_environment = $import_environment DEBUG=1

Configuration

To enable rawlog, you must use rawlog as a post-login script:

service imap {
  executable = imap postlogin
}
service pop3 {
  executable = pop3 postlogin
}

service postlogin {
  executable = script-login -d rawlog
  unix_listener postlogin {
  }
}

You can also give parameters to rawlog:

-b: Write IP packet boundaries (or whatever read() sees anyway) to the log files. The packet is written between <<< and >>>.
-t: Log a microsecond resolution timestamp at the beginning of each line.
-I: Include IP address in the filename (v2.2.16+)
v2.1 and newer:
- -f in: Log only to *.in files
- -f out: Log only to *.out files
v2.0 and older:
- -i: Log only to *.in files
- -o: Log only to *.out files

Pre-login rawlog (v2.1+)

You can enable pre-login rawlog for all users by telling the login processes to log to a rawlog directory, for example:

service imap-login {
  executable = imap-login -R rawlogs
}

This tries to write the rawlogs under $base_dir/login/rawlogs directory. You need to create it first with enough write permissions, e.g.:

mkdir /var/run/dovecot/login/rawlogs
chown dovenull /var/run/dovecot/login/rawlogs
chmod 0700 /var/run/dovecot/login/rawlogs