> Is it possible to determine the Mail User Agents in use via logging in > Postfix and / or Dovecot?
Assert you're using header-checks with pcre in main.cf: header_checks = pcre:/etc/postfix/header_checks Then add the following to /etc/postfix/header_checks and reload postfix: /^(User-Agent|X-Mailer):/ INFO This prints a log line like: Jul 23 00:34:24 mx2.server.com postfix/cleanup[11568]: 4BBqyS5c2CzTVVPX: info: header X-Mailer: Apple Mail (2.3445.104.14) from client.provider.com[1.2.3.4]; from=<sen...@domain.com> to=<recipi...@otherdomain.com> proto=ESMTP helo=<PCNAME> This might be sufficient for your case but keep in mind what Ralph and Paolo said. Best regards Gerald
