Removal of secondary mail server mail-relay20.c2internet.net

Due to hardware failure the server mail-relay20.c2internet.net is being removed from service.

This server's only role was to operate as a secondary/backup mx to customers requesting this functionality where those customers operated their own primary mail servers.

While initially this type of setup was the norm as the war against spam continues these type of backup servers have been targetted as easy routes in. This brings rise to a few problems;

It's not uncommon for these backup servers to be whitelisted/trusted by the primary server, thus totally defeating any anti-spam techniques they are utilising. The backup servers will accept all mail for the domains where it is told to be the secondary, if when forwarding that email to the primary server the primary server rejects a mailbox as unknown the backup server will want to send a non-delivery report. If the originating email was from a forged email address then these NDR's clog the system further which just puts extra load on the server for no real good reason. Worst case is the NDR's are sent to a valid email address but one which had nothing to do with the original email, at which point the server is generating backscatter which is every bit as bad as spam.

If the primary mail server was to fail most sending servers will now quite happily queue email, notify the sender of any sending delays and generally look after sending the email again after a few minutes when the server comes back up.

With all this in mind will we shortly be removing all entries from DNS for mail-relay20.c2internet.net. The unusual thing here is customers who have been using the service may well see a drop in the amount of incoming spam to that of which they had been used to.

This does not affect customers that have their own secondary mail servers