After upgrading Plesk to 7.5.4 suddenly it was impossible to login to Horde. Checking around I found there was no IMAP on port 141 as required by IMP (according to https://server/horde/imp/test.php) Checking Plesk -> Server -> Services shows POP/IMAP to be stopped. Clicking the [>] start button fails to produce any result. /var/log/messages report: imapd.rc suggests starting IMAPD on port 143. What is this mess?