On the same machine, we were running the original Well Now Health Information Service BBS, off-Internet, and providing Internet email services for our BBS members. And at one point we worked hard to construct an itty-bitty ISP on that machine, too.

Thus, for about 5 minutes :-), we had a need to sort mail on this machine, that was all arriving under just a single POP address.

The more logical and real-world solution to this would've been a dedicated Internet connection and our own SMTP and POP servers. We do have those servers running on this computer, along with DNS, NNTP, and every other fine thing -- but have not been able to afford that dedicated connection.

Mail-Penguin

1. polls multiple POP boxes periodically, then
2. retrieves any waiting mail it finds, and
3. compares header information (a bit clumsily) against the contents of several different files in order to determine who's supposed to get each piece of mail, and finally
4. delivers it, by direct disk write if possible, or by having an SMTP conversation otherwise. (It could as easily have a conversation with a local delivery agent.)

Some of the ideas in it are drawn from similar code that was written in REXX. I wrote Mail-Penguin first in straightforward non-module Perl, then for the heck of it rewrote it to make use of a few *.pm modules. I see there are some mysteries in the "black boxes" of those modules that I haven't quite fathomed yet.

Comments of all kinds are invited and encouraged, here, whether about style, syntax, logic or whatever.

Index to Code Files

• init.html -- variables; could go in a setup file
• main.html -- a "do forever" loop
• logon.html -- uses POP3.pm to make server connections
• fetch.html -- retrieves any waiting mail
• queue.html -- saves incoming mail to unique-named disk file
• redirect.html -- secondary Main, directs routines for determining whose mail this is
  • see_if_list.html -- looks for posts to local maillists
  • see_if_sent.html -- looks for "known senders" including maillists
  • see_if_user.html -- looks for aliases of local receivers
• rewrite.html -- rewrites mail headers based on previous routines' findings
• sendmsg.html -- writes or mails email
  • diskdel.html -- writes local-user email to disk file
  • smtpdel.html -- delivers email via SMTP host
• time.html -- utility, notifies user at console what time polling began
• getnext.html -- utility, gets next sequential number for file names