Cyrus IMAP Server: Special Characters

This document is supposed to be a repository of “special characters” used in Cyrus naming of users, folders, directory paths, etc.

Current Uses


Character: +
  • (LMTP) Separation of postuser and target mailbox for delivery
  • (LMTP) Separation of username and submailbox for delivery
  • (IMAP) Flag at end of login name that indicates that LIST should return LSUB results (when imapmagicplus is set)
  • (POP3) POP a subfolder directly (e.g. rjs3+foo POPs user.rjs3.foo)

Character: . /
  • [mailbox names] Hierarchy separators

Character: ^
  • [mailbox names] In unixhierarchysep, ^ is the part of the internal name that represents a ‘.’

Characters: @ %
  • [usernames] These are realm separators for the purposes of authentication

Future Uses

Character: +
  • IMAP LIST filters (e.g. rjs3+foo will only list folders that match foo*)
  • possibly other interpretations here: - rjs3+foo will do an effective chroot(foo.) - rjs3+foo will only list folders in user.rjs3.foo*