Debian 8.10 ISPConfig 3.1.9 php (cli) version is 5.6.30-0+deb8u1 The Perfect Server - Debian 8.4 Jessie (Apache2, BIND, Dovecot, ISPConfig 3.1) Currently unable to send or received email. Server was sending/receiving email OK for months (years?). Mail Error log (select entries: [..] mail postfix/cleanup: error: unsupported dictionary type: tcp [..] mail dovecot: auth-worker(16443): Error: mysql(localhost): Connect failed to database (dbispconfig): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) - waiting for 1 seconds before retry [..] mail dovecot: imap-login: Error: read(anvil) failed: EOF A web search found little information on the 'unsupported dictionary type: tcp' error. Some use postsrsd to correct this issue but this hasn't solved the problem. Postsrsd is installed on the server. After following the Perfect Server Debian 8.4 tutorial to reinstall, did run the ispconfig update.php script.