migrate to Exchange Online without MAPI


We are currently planing to migrate from an hosted exchange provider to Exchange online (O365). We are planing to do a cutover migration. When creating an migration endpoint the connection fails when trying to connect to the MAPI Server. It seems that in contrast to what https://support.office.com/en-us/article/Cutover-migration-to-Office-365-9496e93c-1e59-41a8-9bb3-6e8df0cd81b4#ID0EAABAAA=Run_a_cutover_migration states the migration client requires MAPI access. The Current Provider does not allow MAPI access. Currently only RPC over HTTP is supported. We might have the option to enable MAPI over HTTP and potentially MRS Proxy. I can not find the information if the migration process support MAPI over HTTP instead of MAPI.

Can you tell me if 1. The Microsoft Migration support MAPI/HTTP 2. The Microsoft Migration support MRS Proxy

Thanks in advance Clemens

UPDATE 22.09.2017: The following Error is shown when trying to connect to the server. I also used the "Remote connectivity analyzer" to test the connection and get the autodiscover XML. I got the exchange and RPC/HTTP server from that xml.

MapiExceptionCallFailed: Unable to make connection to the server. (hr=0x80004005, ec=1249) Diagnostic context: Lid: 49064 dwParam: 0x3 Lid: 59431 EMSMDB.EcDoConnectEx called [length=147] Lid: 34855 EMSMDB.EcDoConnectEx returned [ec=0x4E1][length=56][latency=31] Lid: 59505 StoreEc: 0x4E1 Lid: 50544 ClientVersion: Lid: 51056 ServerVersion: 14.3.351.4000 Lid: 52080 StoreEc: 0x4E1 Lid: 51152 Lid: 52465 StoreEc: 0x4E1 Lid: 60065 Lid: 33777 StoreEc: 0x4E1 Lid: 59805 Lid: 52487 StoreEc: 0x4E1 Lid: 19778 Lid: 27970 StoreEc: 0x4E1 Lid: 17730 Lid: 25922 StoreEc: 0x4E1
asked on Server Fault Sep 21, 2017 by Clemens Bergmann • edited Sep 22, 2017 by Clemens Bergmann

1 Answer


Just some other possible options here, if you do not find a way to do that via MAPI over HTTP.

Option 1 (via IMAP):

  1. Enable IMAP on Exchange Online (aka Office 365)
  2. Using IMAP and then performing an IMAP sync task

However this will not take over the agenda or contacts. That would be an per user approach using the Outlook client (Import & Export).

Option 2 (via two mailboxes and Outlook):

  1. Create the mailboxes on Exchange Online
  2. Cut over the MX record from your domain
  3. on your old environment put forwarder in place to user@xxx.onmicrosoft.com (or something like that)
  4. Map both mailboxes on the users and inform them to use only the new one whenever possible. Over the time emails will be only in the new mailbox. You can also move elements from one mailbox to another via the Outlook client then. Or you can let the users perform that.

Option 3 (via local PST file):

  1. Create the mailboxes on Exchange Online
  2. Cut over the MX record from your domain
  3. Let your users move there stuff into a PST file, and then let them re-import

Note here: This approach often destory the "last changed" timestamp, so an archiving isnĀ“t working as expected for these elements as there is now a new timestamp. This often is confusing a backup software. We saw that this will also destoy re-occouring meetings and a re-schedule is no longer working as expected.

answered on Server Fault Sep 21, 2017 by BastianW • edited Sep 25, 2017 by BastianW

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