Question
IMAP supports remote folder manipulation, multiple folder support and multiple simultaneous access to mailboxes. Sporadically users are noticing mail marked for deletion by their IMAP client cannot be purged from the server. An error is returned to the client indicating that the folder is multiply accessed. Why is this?
Answer
This could mean one of two things
- The mailbox in question is being simultaneously accessed by more than one user.
- The same client has made a second connection to the same mailbox without closing down the first connection.
Clients such as Microsoft Outlook will periodically issue multiple connections to the same mailbox. Each connection to the server is unique and is of no relation to the other. The effects of both the above options on the server are similar.
Envisage the scenario of two users access a mailbox for a particular account. Each users client is able to interact freely with the server, with the exception of purging. However these purge commands will be queued internally by the server and run the next time the mailbox is available.
The purpose of this is to protect the clients, if GMS allowed either client to purge mail without the knowledge of the other then to all intents and purposes mail is removed from under the client. This could lead to apparent eratic behaviour within the client and so is not allowed.
See Also:
- What is IMAP4?
- What is POP3 and how does it compare to IMAP4?
- Are GMS Webmail and MS Outlook interchangable as mail clients?
Keywords:imap delete purge expunge multi access