are you CERTAIN that the routine is literally removed from the free version? I know it is common marketing practice to simply remove the UI portion of a package so that the function appears to be missing [incentive for the customer to move up a notch], when in fact it is present and working in default mode.
approaching this from another direction: it is certainly true that AVAST 5 Free is scanning mail [assuming the feature has not been manually stopped]. So, what is it doing with any message that it sees that run afoul of its parameters?
And once it sees a "bad" message, does it necessarily flag each/every instance of the same to the attention of the User? I know the AVAST team takes great care to minimize the interruption of the user so I'm wondering what is going on under the hood.
Stopping the realtime mail scanner has no effect on the things I'm watching and looking for. This would seem to support the idea that something local to the client-machine has "marked" for extinction any message incoming from the certain senders - the incoming message arrives unmolested at the ISP, then the local mail client [OE6] logs-in and fetches the message, marking it "read" [I think... not really certain how that exchange works], then the message never appears anywhere in the OE6 database so far as I have been able to ascertain. With the flag set to "leave copy on the server", the message is intact at the ISP's 'inbox'.
I keep trying to blame it on OE6 but there are no error messages whatsoever in OE6, and when you really examine the package, there is just not much to it that could conceivably SELECTIVELY and Automatically block just a few routine senders. The "blacklist" function within OE6 is entirely manual, not automatic, and best I can tell it is void of any junk filtering. At the ISP level, just for good measure, we have all these users whitelisted. So I'm down to just a couple of items that have the ability to selectively, blindly, and automatically 'tag' an incoming message as 'bad' and disappear it to the bit-bucket. AVAST is the best candidate. Turning off the Windows Firewall [which has no mail screening function anyway] was neuter, and the router in use, though it has the common garden variety firewall, has no ability to screen mail fetches.