A fast and robust implementation of the RFC1939 POP3 protocol.
It supports both BSD-type and SysV-type mailbox formats. Cucipop
assumes that the mailbox it serves is not simultaneously accessed
by a mailreader.  Concurrency and locking issues are handled
graciously if they restrict themselves to the mail delivery agent.

Feature summary for cucipop:
	+ It's fast (optimised for frequently polling POP3 clients)
	+ It's less filling (i.e. small)
	+ Does not use *any* temporary files (which also means that the
	  startup time is spectacularly short, and there can never be
	  any stale temporary files or doubled mailboxes)
	+ It can therefore serve *any* size mailbox without requiring
	  additional storage beyond what the file already occupies
	+ A fully compliant, all frills attached, RFC1939 implementation of
	  the POP3 protocol
	+ This means that it supports APOP *and* UIDL
	+ It includes the option to sabotage the UIDL command (to defeat
	  undesirable "Leave mail on server" clients)
	+ It also supports an optional autodelete mechanism, so that any
	  RETReived message is automatically deleted
	+ Autoadaptive, simply start it and it will know if it has been
	  started from inetd or as a standalone daemon
	+ Security conscious, i.e. the APOP support, already has hooks
	  for shadowpasswords, and defeats password guessers by an adaptive
	  verification delay
	+ Supports both BSD and SysV (Content-Length) mailbox formats
	+ Native support for /var/spool/mail/b/a/bar type mailspools
	+ Is the only popd to perform reliable mailbox locking across
	  NFS as well (it uses the same excellent and proven locking
	  algorithms as does procmail)
	+ Provides flexible logging of statistics and auditing events
	+ Does not impose *any* limits on line lengths, mail length,
	  or the use of any character (any 8-bit character, including '\0' is
	  allowed) in the mail
	+ Secure system mailbox handling
	+ Has hooks to ease moving the mailboxes to any location you'd like
	+ Has hooks for other authentication schemes (e.g. Radius)
	+ Has hooks to virtualise the popserver
	+ It runs on any POSIX and ANSI C compliant system
	+ Is clock skew immune (e.g. in the case of NFS mounted mailboxes)

- Igor
igor@zynaps.ru