Spam and virus filtering

Mailboxes are protected by spam and virus filtering. All incoming and outgoing mail is scanned with ClamAV, and messages found to be containing a virus are rejected. There are also multiple anti-spam measures in place:

When a message is rejected, the error message will explain to the sender exactly why it happened, so that legitimate senders can attempt to fix the problem.

Additional options are available if necessary, such as per-user Bayesian filters like QSF.


Incoming connections are only allowed to the standard services on their standard ports. Other ports can be opened for listening but attempts to connect to them from outside will fail. This reduces the spread of worms and other malware.

Incoming connections are also rate limited, and in some cases, exceeding the rate limit will result in a temporary blacklisting of the connecting IP address. This reduces the risk from automated password guessing scripts.

Outgoing connections are also limited to specific ports, and rate limited.

These restrictions are in place to help ensure system security. If you have a valid reason for any of them to be relaxed, please use the Contact Form to discuss it.