This is my first post and do not know if this is permitted, please advise if it is not.
I have my own mail server running on Exchange. Spammers seem determined to over take some of the inboxes on this server. I have configured antispam options on Exchange, I use OPNSense as my router and have blocked traffic to certain countries, especially those known to send a lot of spam, I have setup a firewall rule to block spam known to SpamHaus. The statics for both firewall rules show they have blocked a significant amount of traffic. Yet spam is still getting through.
What I would like to do now is set up a spam server using SpamAssassin running on the latest version of Ubuntu Server. However, I am having trouble finding a good guide to setup and configure SpamAssassin.
I have Ubuntu Server 24.04 installed as well as SpamAssassin, but do not know what the next steps are.
Before we deep dive into this, have you considered getting a more robust commercial-grade antispam system first? I ask this because fine tuning your SpamAssassin rules and handling blocks/quarantines for false positives is going to be Difficult, and will also require a TON of time and effort on your part training SpamAssassin rules, even if you start with a robust ruleset from third party sources.
I ask this because Email Security is almost its own full-time job in its own right, and as someone who does IT Security stuff regularly, you really may want to consider not doing this yourself piecemeal, but going with readily available commercial antispam solutions with mail gateways, etc. instead.
And no, I don’t want to drive you away from doing this yourself with Ubuntu, but the level of complexity this entails is Very High hence my initial inquiry.
I did use to use Spam Hero for one domain. I now have multiple domains and they charge extra for each one. As an IT services provider I use AVG Cloud Care, after leaving Spam Hero I used AVG’s spam filtering service however, AVG shut down that service several years ago.
Shortly after AVG shut down their spam filtering service, I installed, configured and used the free version of Xeams, but they limit the free version to 5 users and I have more then that. So while my Xeams server is currently running filtering is disabled. I cannot afford to pay the monthly fee they want for more than 5 users.
I was advised on another non Linux forum to strengthen the antispam rules on Exchange but I am unable to find a guide on how to do that.
I did just discover that the spam blocking rules I set up in OPNSense were not updating as required. I also discovered that my GeoIP update link was not working. Both of these have been resolved so hopefully with these two changes alone the amount of spam I get will significantly be reduced.
My thoughts and hopes are that if I can get a antispam server / filter setup, strengthen the rules for Exchange and with the above mentioned firewall rules, spam will become a non issue. I did look at EFA project but it is no longer maintained.
Although I work in IT, I am sure you can tell I am not an expert in the area of email and email security. I built my network in part to learn and for the experience. I am prepared to spend some time to train a spam filter (whether Spam Assassin or something else). Although, I will say I do not want to spend hours upon hours everyday doing so. I would prefer to have an “in-house” solution, but I am willing to use something else if there is something easier or better. Spam Assassin is the only one I can find that is open source (IE free) and allows unlimited email accounts
I have not used Spam Assassin in the past so I do not know how their rules work or are created. However I have been training Outlook, with multiple accounts, as far as what emails to block for years, and can export these address’ and import them into Spam Assassin (or what ever solution I go with) if possible.