I recently installed a product called Open Relay Filter (Enterprise Edition) (ORF) (http://www.vamsoft.com/orf/). This is an add-on to IIS SMTP which checks email against a series of rules and open relay lists. This is a VERY nice program, however, it has a problem with POP3.
ORF works like POP3 in that it grabs email from the DROP folder, processes it (decides if it should be deleted, etc.) or leaves it alone if it is legit. Of course ORF and POP3 are both trying to grab email from the DROP folder at the same time. Sometimes POP3 wins and sometimes ORF wins. Either way, this is a problem.
As a temporary fix, I have SMTP dropping email into a different folder. ORF processes it from that same folder then, I have a looping batch file move the *.EML files into the DROP folder POP3 is looking at. This is not a very elegant solution.
A programmer friend is going to write me a Win2k service to do what the batch file is doing but, I'm wondering if DawkCo can offer a better solution.
If you want to take this to email. Please feel free to contact me at the address I am using for this posting.