The POP server is available via anonymous ftp from 
ftp.qualcomm.com:/quest/unix/servers/popper
  The makefile supports AIX
ftp.CC.Berkeley.EDU (128.32.136.9, 128.32.206.12).
  There are two versions in the pub directory: a compressed tar file
  popper-version.tar.Z and a Macintosh StuffIt archive in BinHex format
  called MacPOP.sit.hqx.

Problems building some versions of popper can sometimes be resolved by
compiling with bsdcc or -D_BSD.

The pine 3.95 package on <http://www-frec.bull.com/> contains "plug
and play" support for both POP3 and IMAP mail reading protocols.  You
can also get a compiled version of qpopper 2.2 there also.

Some parts © 2009 Advameg, Inc.