Hi,

I'm running Exchange 2013 SP1, using KEMP as load balancers in front - SSL Offloading is enabled. After some of my users have started to use MAPI over HTTP, our IIS logs has started to grow rapidly.

I see alot of there lines in the log:

2014-04-28 09:55:22 172.16.25.204 POST /mapi/emsmdb/ ;&cafeReqId=73899dcb-cb47-4820-8d19-a84719a53127">MailboxId=06523f9d-604a-48e1-8f75-a450fa80dccd@kromannreumert.com&CorrelationID=<empty>;&cafeReqId=73899dcb-cb47-4820-8d19-a84719a53127; 80 - 172.16.25.91 Microsoft+Office/15.0+(Windows+NT+6.2;+Microsoft+Outlook+15.0.4551;+Pro) - 401 1 2148074254 15
2014-04-28 09:55:22 172.16.25.204 POST /mapi/emsmdb/ ;&cafeReqId=b02eadc9-c875-4ec8-9c7a-7df2c5bc565a">MailboxId=06523f9d-604a-48e1-8f75-a450fa80dccd@kromannreumert.com&CorrelationID=<empty>;&cafeReqId=b02eadc9-c875-4ec8-9c7a-7df2c5bc565a; 80 - 172.16.25.91 Microsoft+Office/15.0+(Windows+NT+6.2;+Microsoft+Outlook+15.0.4551;+Pro) - 401 1 2148074254 15
2014-04-28 09:55:22 172.16.25.204 POST /mapi/emsmdb/ ;&cafeReqId=b64fbfbd-9e77-4356-a272-c6f5250863eb">MailboxId=06523f9d-604a-48e1-8f75-a450fa80dccd@kromannreumert.com&CorrelationID=<empty>;&cafeReqId=b64fbfbd-9e77-4356-a272-c6f5250863eb; 80 - 172.16.25.91 Microsoft+Office/15.0+(Windows+NT+6.2;+Microsoft+Outlook+15.0.4551;+Pro) - 401 1 2148074254 15
2014-04-28 09:55:22 172.16.25.204 POST /mapi/emsmdb/ ;&cafeReqId=96617663-dd0d-4c10-8f53-24e9a1284503">MailboxId=06523f9d-604a-48e1-8f75-a450fa80dccd@kromannreumert.com&CorrelationID=<empty>;&cafeReqId=96617663-dd0d-4c10-8f53-24e9a1284503; 80 - 172.16.25.91 Microsoft+Office/15.0+(Windows+NT+6.2;+Microsoft+Outlook+15.0.4551;+Pro) - 401 1 2148074254 0

I understand, that it first try to auth. without username, and then Again using username, but howcome it does this Again and Again?

I don't see this, on users running RPC over HTTP?

Regards

Allan

Hi,

To resolve the MAPI over HTTP issue, I'd like to recommend the following troubleshooting:
1. Check the settings of MAPI virtual directory: get-mapivirtualdirectory |fl
2. Does your Exchange 2013 SP1 install on Windows 2012 R2 server?
3. Verify if your load balancers, reverse proxies, and firewalls are configured to allow access to the MAPI over HTTP virtual directory.
4. How about the result of testing the end-to-end MAPI over HTTP connection by the following command?
Test-OutlookConnectivity -RunFromServerId ContosoMail -ProbeIdentity OutlookMapiHttpSelfTestProbe

Thanks,

Hello Allan,

I know this is a very old thread here but did you ever get this Problem solved? I still fighting with this MAPI Problem. User gets Password prompt when opening Outlook. Just clicking cancel, closing and opening Outlook Server times helps to get connected correctly and one Point. This MAPI is very annoying. Never had Problems with RPC. Running Exchange 2013 CU8 at the Moment.

Cheers

Robert

Check and  verify your reverse proxy and the load balancers.

Check the authentication of the mapi virtual directory.

Hi,

thanks for the response. I've only one CAS server and it's internal connection. So no LBs, no rev. proxies in between. Direct connection.

Regards

Robert