OWA Deleted Contact Keeps Coming Back CU19

Question

On prem Exchange 2016 CU19 - a user has emailed an incorrect address using the OWA / Webmail portal. They receive a bounceback, and resend the email with the correct address. The incorrect address is still in the autocomplete cache.

In the Outlook client we can click the "X" on the autocomplete contact, and it goes away. In Webmail, we can do the same thing and click the "X" and it goes away, but after logging out and logging back in, the autocomplete contact keeps coming back.

I even created a new account - sent one incorrect email - and deleted every message in the mailbox (inbox, sent, drafts, deleted items, EVERYTHING). And I still can't get the autocomplete cache to go away.

I dont recall having this issue on CU17 .. wondering if anyone else has the same issue on CU19?

Answer 1

Hi,@Greg Kopoian

I tested in my lab (Exchange 2016 CU13, Exchange 2016 CU19 and Exchange 2019 CU1) and was able to reproduce the problem in all these environments.
It seems to be by-design because of OWA autocomplete cache which is stored in the mailbox.

As a workaround, you may use MFCMapi to delete the cache.
You can get this tool via : https://github.com/stephenegriffin/mfcmapi/releases/tag/20.0.20307.01

To use this tool, you need a Outlook client which is configured with the affected account's profile and also in Exchange online mode.
Here are the detailed steps:

1. open MFCMAPI.exe, locate Session>Logon and select the user profile
2. double click to open the file
3. right click on Root containe" and select Open associated contents table
4. check if there are items which has a message class named "IPM.Configuration.Owa.AutoCompleteCache"
   if there are, Right Click on the item and select Delete message>Permanent deletion (delete to deleted items retention if supported)
5. back to Root container and locate Top of information store>Contacts>Recipient Cache
6. delete the folder or delete the items in the folder ( Please note it may delete other contacts with correct addresses as well)

Then you may open OWA and check if the problem persists.

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Answer 2

Hey KaelYao,

Thanks for the advice and testing in your lab - it worked like a charm!

I actually went one step further, I did NOT delete step 4 .... I continued on to step 5 and in step 6, instead of deleting the "Recipient Cache" i chose to "Open Contents Table".

Then I was able to search through a large list of autocomplete contacts (painful), and locate and delete just the problematic one.

Either way this looks like a great solution and I have saved it for future use. Thanks again.