Since a day or two the mail delivery queue of the hMailServer is exploding because someone is trying to send spam via this server. Though the e-mails aren't successfully sent it fills up the mail queue.
All SMTP connections require smtp-connections and also the log shows '530 Authentication Required'.
Also the mails are sent via a non-existing mail-account. (Service@website.com)
Below images show the queue and a part of the log.
Is there anyway I can stop the queue from filling up? Auto-ban is enabled but doesn't seem to help.
Best Answer
The first thing I would try is to configure some dns RBL, http://www.hmailserver.com/documentation/latest/?page=reference_antispam
If it is correctly implemented you will have messages blocked before the SMTP exchange has begun, and nothing created in the queue. You could begin with spamhaus xbl and/or sbl, there are relatively safe and might greatly help your problem.
The second thing I would do is have a look at the COM api:
You have a
DeliveryQueue
object which you can use to clear the queue. This might not be the best solution but it's always better to script it and run it on a scheduled task than having to open the gui and click manually on "Clear Queue". Once you have a basic script you can enhance it, for example by running the Clear() only if the queue size is above a certain threshold..Then if the incoming traffic is so high that even with some good DNS RBLs and big automated clearing of the queue your server can not stand the traffic I would look for setting up an MX server somewhere else and configure it to shield your server from such attacks. A lot of unix-based server will probably handle these situations more efficiently, and you can have one on a vps for a small monthly amount.