Mail cannot access your mailbox information because it’s already in use

Mail.app has started popping up this error on a 2017 iMac 21 fusion drive Monterey 12.6.1


"Mail cannot access your mailbox information because it’s already in use"


Restarting Mail makes it go away for awhile and the iCloud account will send and recieve. Googling finds a few short unproductive discussions of this exact same error message over the last 14 years. This screenshot of the full error adds to the mystery.


Anyone had this problem? And fixed it? Or at least understood it?



iMac Line (2012 and Later)

Posted on Dec 14, 2022 04:46 PM

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Dec 17, 2022 01:27 PM in response to dallasmacguy

Hello dallasmacguy,


Have you been able to try selecting the 'Rebuild Mailbox Information' option? If not, that may be able to help out. This page can help out with providing information on rebuilding mailboxes: Rebuild mailboxes in Mail on Mac


When you rebuild mailboxes for IMAP or Exchange accounts, messages and attachments stored on your Mac are discarded, and then downloaded again from the mail server to your Mac. Your mailbox appears empty until the download is complete.


As the alert notes, be sure to also check and see if there are any other apps on the Mac or network accessing the mailbox info. To help rule out devices on the network, you may try temporarily turning any others off that are currently on and connected.


Cheers.



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Mail cannot access your mailbox information because it’s already in use

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