Free Roundcube skin
A mailing list manager with an excellent web interface
Free and open source webmail software
Open Source Anti-Spam and Anti-Virus Gateway
Source code for be able to use Relation Tags.
A simple library for sending emails with or without attachments
Zimbra Backup and Restore
send mass mail
OpenSource high performance mail policy daemon for Postfi
Send mails per SMTP in a predefined interval
Ciphermail email encryption gateway (S/MIME, OpenPGP, PDF encryption)
Smart Card Sniffing And Debugging Tool for contact based SIM/ME comm.