MailCleaner Open Source Edition is now discontinued but will continue under the spamtagger project
https://github.com/SpamTagger
[antispam] MailCleaner is an anti-spam / anti-virus filter SMTP gateway with user and admin web interfaces, quarantine, multi-domains, multi-templates, multi-languages. Using Bayes, RBLs, Spamassassin, MailScanner, ClamAV. Based on Debian. Enterprise ready.
MailCleaner is an anti spam gateway installed between your mail infrastructure and the Internet.
It...
openlsm - Web based open source, Linux Server Management(LSM) -LAMP ,FTP,Jabber, Samba,NFS,LDAP and MySQL based virtual hosting, Squid,Backup,Quota,Mail ,spam-assassin, mailable,Asterisk, web hosting, Load balancing, nagios and ganglia monitoring.
Unlimited organizations, 3 enterprise SSO connections, role-based access control, and pro MFA included. Dev and prod tenants out of the box.
Auth0's B2B Essentials plan gives you everything you need to ship secure multi-tenant apps. Unlimited orgs, enterprise SSO, RBAC, audit log streaming, and higher auth and API limits included. Add on M2M tokens, enterprise MFA, or additional SSO connections as you scale.