I have an end user with 99,500+ contacts including the Recipient Cache. We're doing an O365 Tenant to Tenant migration. Every time I try to do a full mailbox migration it stalls with this warning: "The server cannot service this request right now. Try again later. Waiting 5.00 minutes before resuming". It'll keep saying that forever. I have a support case open, but I'm trying this avenue as well. Support asked if there is a folder with a lot of items. 99,500 items is a lot, but we had many other users with many more mail items, and there were no issues with their mailboxes. I was able to migrate everything else in this mailbox by excluding contacts. This issue only happens when I try to migrate contacts. Working on support's theory of too many items in a folder, I split the Contacts folder into sub folders with 23,649 or fewer contacts each (a very tedious process manually using Outlook). I till keep getting the same "The server cannot service this request right now. Try again later. Waiting 5.00 minutes before resuming" issue. I could keep splitting contacts into more folders, but I have a feeling that Quest tries to get a total Contact count from all folders and then runs into this issue. Running "Get-MailboxFolderStatistics firstname.lastname@example.org -folderscope contacts | select identity, itemsinfolder" returns the count across all folders almost instantly.
Thoughts? Am I going to have to resort to using Outlook to export these to a PST, and then re-import them? That'll be disappointing.