Return
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Title
MAPI_E_LOGON_FAILED -
Description
Unable to migrate any public folders from source to target. Getting the error: Error - Failed to create folder '\xxxxx\yyyyy' on server 'O365'. New-PublicFolder -Name "client" -Path "\zzzzz" -Mailbox "GUID" -
Cause
Per the above error, issue is due to throttling occurring on the service account specific to the worker app. In this environment (On premise to O365), 5 workers were available to Exchange Pro. Only one worker had all the roles applied and the service account on the O365 (target) perspective had not been uplifted to allow for more than 3 concurrent PowerShell sessions.
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Resolution
The errors seen where the MAPI logon failure when populating the Public Folder is due to timeouts with the services accounts in scope for this project. Suggested the end-client reach out to Microsoft to uplift the max concurrent PowerShell sessions for the Public Folder service accounts. Currently, they have 5 Public Folders target service accounts and 1 on-prem service account.Suggest the need to increase the number of source service accounts if they still encounter errors.