Although it is know for being THE Windows Usenet (a.k.a. newsgroup) reader, I find that Agent makes a swell e-mail client, too. It--at least as it is configured on my computer--doesn't automatically install viruses for you like (afaik) Outlook will, but you can always install them manually.
Forte Inc. has added a lot of feature to the e-mail side of the program over the many years I've been a customer. I don't use any of them, so I can't advise you on their worth. But they *seem* spiffy.