For plain ole POP3: cucipop
For IMAP & POP3   : imap-uw

I picked imap-uw because it also appears in the ports tree for *BSD.
The last advisory I saw on it was dated: 4-24-2000

The pop only daemons seem to be your best security bet for external
users and keep IMAP for internal use only.

JLF Sends...

It seems like on Sun, Jul 23, 2000 at 10:18:18PM -0700, Digital Wokan scribbled:
Orig Msg> I'm pitching Linux for its stability, not its price.  But I'm also
Orig Msg> pitching the concept of the GPL.  My primary concern is to find a high
Orig Msg> quality GPL'd POP3 server.  I'm not given a budget, so every time I have
Orig Msg> to go to the keepers of the cash, I have to justify every little thing. 
Orig Msg> So free beer as opposed to free speech is at least helpful in pitching
Orig Msg> Linux as the platform since I can bypass needing to justify the cost of
Orig Msg> the POP3 server.  The end goal of all this is to eventually get them off
Orig Msg> the reliance on NT/IIS/ASP.  The bottom line is just one point I'm
Orig Msg> bringing to bear.  Stability is far higher on the list due to all the
Orig Msg> troubles we've had with our host's e-mail servers.
Orig Msg>