Paraphrasing the website:
Mailman is a mailing list manager (MLM); that is, software to help manage
email discussion lists, much like Majordomo, LISTSERV, and the like.
Unlike most similar products, Mailman gives each mailing list a web page
and allows users to subscribe, unsubscribe, and change their preferences
via the web. Even a list manager can administer his or her list(s)
entirely via the web. Mailman integrates many common MLM features,
including web-based archiving (though it also has hooks for external
archivers), mail-to-news gateways, bounce handling, spam prevention,
Majordomo-style email-based list administration, direct SMTP delivery (with
fast bulk mailing), digest delivery, virtual domain support, and more.
Mailman is written mostly in Python (with a smattering of C where necessary
for security purposes), and includes hooks to make it easily scriptable and
extensible. It is compatible with most web servers and browsers, and most
mail transfer agents (mail servers). Mailman's documentation may be found on
its website.
ACL Policy Daemon is a program that communicates with the Postfix MTA using the
Policy Delegation Protocol implementing an ACL (Access Control List) system,
making very easy to improve and create nice controls on your e-mail traffic.
You can use it to verify SPF records too.
The libgmail project is a pure Python binding to provide access to Google's
Gmail web-mail service.
Python binding of the notmuch mail search and indexing library.
SpamBayes is a tool used to segregate unwanted mail (spam) from the mail you
want (ham). Before SpamBayes can be your spam filter of choice you need to
train it on representative samples of email you receive. After it's been
trained, you use SpamBayes to classify new mail according to its spamminess
and hamminess qualities.
qconfirm is an implementation of a delivery confirmation process for a mail
address under qmail. It is invoked by qmail-local through a .qmail file.
qconfirm performs this delivery confirmation process either sender based or
message based. It is similar in concept to qsecretary or TMDA.
Elmo (ELectronic Mail Operator) is an ncurses-based program for
receiving, filtering, reading, composing, and sending mail from a
character terminal. It speaks POP3 and SMTP and can work with
maildir or Berkeley-formatted mailboxes.
This version is a development version, but is rather stable, and
is known to work better than the stable version on FreeBSD 4.x.
Before running elmo, users should run elmoconf.pl to generate an
~/.elmorc file.
Elmo (ELectronic Mail Operator) is an ncurses-based program for
receiving, filtering, reading, composing, and sending mail from a
character terminal. It speaks POP3 and SMTP and can work with
maildir or Berkeley-formatted mailboxes.
Before running elmo, users should run elmoconf.pl to generate an
~/.elmorc file.
sendok is a simple program to generate qmail email addresses with timed cookies
in them. That is, you can give someone a generated address that will accept
mail from a given sender for a given time period. The address contains a
cryptographic hash so that no per-address local data needs to be stored.
It's a lightweight, fast and reliable Sendmail milter that implements
a real-time Sender e-Mail Address Verification technology. This technology
can stop some kinds of SPAM with a spoofed sender's e-Mail address.
Also it implements a real-time Recipient e-Mail Address Verification
technology. It can be useful if your machine is a backup MX for the recipient's
domains or if your machine forwards all e-Mail messages as a relay host for your
domains to another internal or external e-Mail servers.
It's a lite alternative for the spamilter, milter-sender and milter-ahead
milters.