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*