We're updating SSL certificates for our legacy email servers today. The old serial number is 130CAB. The new serial number is 1360FD. However, if you are reading this status post because are you seeing the change or a warning message then you are probably using out of date settings. Please change your POP3 or IMAP server name setting to our new one, which is simply: mail.aa.net.uk
See https://support.aa.net.uk/Email_Settings for more information about email settings