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MilterQuota is a milter (mail filter) for sendmail using libmilter.

The problem was: If you wanted the mailbox of a given user to be full at a given size there was only one solution: disk quotas. But unfortunately if the inbox was full the user was also unable to work on the system. He has to delete some files or mails from his mailbox first to free some diskspace.

This is the kind of problem MilterQuota solves: It implements quotas for inboxes without any influence on the disk space that is offered to the user under a shell environment. So it is possible to restrict mailbox sizes without limiting work space.


  • one central configuration file
  • definable default inbox size for all users
  • per user definition of the inbox size (if not defined the default is used) with ability to disable the limit
  • definable override-address: mail originating from this email address will always be delivered even when the inbox is considered as full

In case a mailbox is full and a mail cannot be delivered MilterQuota rejects the mail with an error message generated by the MTA (usually sendmail) to inform the originating sender that the mail was rejected because the user's mailbox is full.

Upcoming features in the next release(s) of MilterQuota

  • definable inbox location (for use with IMAP-daemons)
  • PostgreSQL-support (put the configuration data into a postgres-db)


Click here to get the latest version or have a look at our download page or the FTP-server!

MilterQuota is still under development but it works stable. We would appreciate your help to this project in testing and sharing your experiences with us. Just drop us a mail.