Another tough case of MAPI_E_FAILONEPROVIDER mailbox access error

October 26, 2016

This case is another one of those countless issues which reminds you every day that no matter how long you have been doing migrations you can never rest on an old knowledge and experience. Rather you need to keep learning something new which may at first appear same old, that’s a nature of our job 🙂 Everyone have probably seen MAPI_E_FAILONEPROVIDER mailbox access error thousands of times and knows it may be caused by name resolution, permissions (mostly)… I have also seen some “exotic” cases where same LegacyExchangeDN was present on the proxyAddresses attribute of another recipient (Contact) preventing both Mail Sync Agent access and end user’s Outlook MAPI login. But I bet the one I am about to describe is not something you’d encounter often.