World: r3wp

These both work well with Gmail (extensively tested):

http://www.rebol.it/power-mezz/schemes/imapcommands.html
http://www.rebol.it/power-mezz/mezz/imap.html

Unfortunately the documentation is not very good, but it shouldn't 
be too hard to figure out where it differs from the actual code. 
Also, if you grab the repository from Sourceforge, there are a couple 
bug fixes to mezz/imap.r