Office 365 IMAP migration between tenants

New Contributor


i've an issue performing bulk IMAP migration of Office 365 mailboxes from one teannt to another.

I need to move mailboxes using migration admin account, for that i provided FullAccess rights to the admin account on all mailboxes to migrate:

Get-Mailbox -ResultSize unlimited -Filter {(RecipientTypeDetails -eq 'UserMailbox')} | Add-MailboxPermission -User -AccessRights fullaccess -InheritanceType all

No problem with connecting to exchange online, creating endpoint, batch

the csv file foramt is:


the csv format file is correct ? i can't find any information regarding this on MS KB

Batch failed with this error :

Error: TooManyTransientFailureRetriesPermanentException/ImapTemporaryServerErrorException/ImapBadResponseException: Error: The job encountered too many transient failures ‎(61)‎ and is quitting. The most common failure is ImapTemporaryServerErrorException/ImapBadResponseException with the hit count 60. --> Imap server has encountered a temporary error. --> Imap server sent BAD response to ListCommand. Response code: ‎'‎', message: ‎'User is authenticated but not connected.‎'.

Any ideas Please ?

Thank you.

2 Replies
@M_MAdmin... What happens when you migrate 1 mailbox instead of bulk at first instance? Test and you may see a more detailed error than while performing a Bulk operation.


I got the same error message when migrating a single mailbox with his password (inseated of using admin account)


I found the problem, my destination tenant has expired, I initially used to create it and the 90 days expired now.


Thank you for your help