BSD Vacation v2 is a rewrite of the 'vacation' program that has come with Sendmail (and thus *BSD) since about 1983. This version has been almost completely rewritten in an attempt to get it closer to RFC-2822 compliance than any previous version. It properly responds to the correct recipients, as per the RFC, and it correctly handles multi-line headers. The command-line interface is compatible with previous versions, and most recent add-on features from the various *BSD projects have been implemented, such as support for preloading the recent recipients database.
SMTP client class is a PHP class that connects to a mail server to send messages. It can relay message delivery to a defined server or directly deliver messages to a recipient's server for urgent message delivery. It supports secure connections with SSL or starting TLS after the connection is established, connection timeouts, authentication using PHP SASL class (PLAIN, LOGIN, CRAM-MD5, NTLM), POP3 before SMTP delivery authentication, and takes advantage of the SMTP PIPELINING extension to buffer SMTP commands, providing much faster queueing of messages when delivering to a large number of recipients (bulk mail).
Elm Millennium Edition is a text-based mail client. There are two branches: Elm 2.4ME+, which is based on Elm 2.4, and Elm ME+ 2.5, which also incorporates some code from Elm 2.5. Elm Millennium Edition contains enhanced MIME and character set support. A subset of UTF-8 (Unicode) is handled. It can read mail from a local mbox and POP and IMAP folders and can pass mail to the PGP or GPG programs. It can also view digests as a mailbox and reassemble fragmented (message/partial) messages. It includes modules for TLS/SSL, iconv, and SMTP.