During a migration from domino to exchange i have run into following error. Mapi session /o=mydomein/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=f47163f497bb4c02b5b43d861bb35136-Admin Dell Mig with client type MoMT exceeded the maximum of 32 objects of type Session. Default there are some limits to how many sessions one user can have or even how many objects one user can open (i think it was 500 per user session) to solve this you have to edit the registery on your exchange server this worked for exchange 2016 https://technet.microsoft.com/en-us/library/ff477612(v=exchg.141).aspx adding the "Maximum Allowed Sessions Per User" solved the problem of the migration user to have more then [...]