Apple Mail file
File type: Various data file
The .imapmbox file is a mailbox container used by Apple Mail, Apple's email client for macOS.
It stores local copies of email messages and associated attachments from an IMAP email account.
File type category:
Various data file
Date updated: September 27, 2026
Apple Mail uses the IMAPMBOX file extension for mailbox data associated with IMAP accounts. The file acts as a container for messages and attachments that Apple Mail keeps locally while synchronizing with the mail server.
The data is part of Apple Mail's account storage rather than a standalone document intended for exchange. Apple Mail manages the mailbox and its contents, including the message files and supporting data inside the container.
Apple Mail is included with Apple's macOS operating system, formerly called Mac OS X. The .imapmbox format is an internal storage format and is not generally used as a current, portable mail format.
Open the associated IMAP account in Apple Mail on macOS to view the messages. The .imapmbox file is a mailbox container managed by Apple Mail, so it normally cannot be opened meaningfully as a separate document by another application.
Do not edit or move the file while Apple Mail is using the account.
The .imapmbox file is not normally converted directly. Apple Mail can export the mailbox to the standard .mbox format, which is more suitable for transferring or archiving messages.
Because the mailbox is synchronized with an IMAP server, messages can also be recovered by adding the account to Apple Mail and allowing it to synchronize again.
Software applications that handle other tasks involving imapmbox files:
Apple macOS / Mac OS X
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