I am trying to come up with a good spam filtering solution for a business with around 15-20 users, each user running multiple POP3 accounts. Many of these accounts are fairly generic "info@" accounts, and as such, they tend to receive quite a lot of spam to the point where it is starting to become a serious problem. Users are all running Thunderbird (with maybe one or two of them running Outlook 2010).
I am going there today to confirm that they actually have Thunderbird's junk settings enabled and configured, but I have a feeling I'll probably need more than that for the amount of emails they receive daily. The business has a SonicWall in place, but from what I can tell, the SonicWall's anti-spam service doesn't work with Thunderbird (it apparently has a client program you can run on workstations to make it work with POP3 accounts in something like Outlook, but I saw no mention of Thunderbird support), not to mention that the SonicWall model they have is discontinued anyway.
Can anyone make any recommendations? I'm having a difficult time finding a solution that works with Thunderbird.