There have been a couple of changes to the local mail services recently. None of which Informatics users should have noticed, but for the record.
mail.inf.ed.ac.uk now only relays from Informatics machines
Due to a misconfiguration, mail.inf.ed.ac.uk had been allowing any machine within the University’s network to relay mail through it. This came to light when a compromised machine elsewhere in the University was sending spam out via us. This is now been tightened up, and only machines on the Informatics network can freely relay mail via mail.inf.ed.ac.uk.
smtp.inf.ed.ac.uk is now running fail2ban
The smtp.inf.ed.ac.uk service has been upgraded to SL7, and at the same time is now running fail2ban. This means that repeated, successive authorisation failures from an IP address, will result in that IP address being denied access for a period of time. This is to stop the bad guys from trying to brute force your password. This is similar to the steps taken on the external ssh access machines.