A great tip for Dutch readers: if your company is experiencing uncurable spam problems, try Onlinespamfilter.nl.
Making onlinespamfilter.nl work is very simple:
- Have Jasper Toonen @ Onlinespamfilter.nl create a 30-day trial account for you; this will involve telling him at which IP address the scanned mail should be delivered; most of the times, this will be the public IP address of your private mail server on the LAN;
- Remove any existing MX-records from your domain;
- Add two MX-records for the scanning servers at onlinespamfilter.nl;
- C'est ca!
Additional changes can be made to your firewall or mail server, but basically this is all that is required.
The result of all this is a practically spam-free and virus-free mail flow! Really, almost no spam is coming thru. And although onlinespamfilter.nl's services are mainly to prevent spam for your domains, they do provide virus-scanning as well. (As Jasper says: spam filtering is a lot harder to do than virus scanning is; and, hey... as we're already scanning your mail for spam, let's also do virus scanning, while we're at it...).
Check it out!