Mailboxes and SPECIAL-USE

Traditionally IMAP clients have automatically created Sent, Spam, etc. mailboxes themselves and used various different names for them. This of course makes interoperability between clients difficult. So SPECIAL-USE IMAP extension was developed to allow clients to determine which mailboxes should be used for which purposes.

This page could be helpful for IMAP server admins to figure out how all of this works in different IMAP clients. The columns mean:

• SPECIAL-USE: Does the client support SPECIAL-USE, and when?
  • no: Not supported
  • once: When account is created. If the server adds/changes SPECIAL-USE configuration it's not picked up unless the account is recreated.
  • always: The client always (or periodically) checks for changes in the server's SPECIAL-USE configuration and either changes its own configuration or asks user what to do.
• Lang: ISO language code, e.g. "en", "de", "it".
• Configurable: Are the mailbox names configurable by user?
• \Fields: Name of the mailboxes that the client creates when it doesn't use the server's SPECIAL-USE names.
  • \All and \Flagged not included, because I don't think any IMAP clients actually have them?

Please update the table with any clients you know of!