Source of Outlook 2016 Address field dropdown "Other Suggestions"

[Tim Schoeller]

Configuration (may not be relevant to the problem):
Outlook 365 v1712 b8827.2131 click to run.
I have O365 account as primary with several shared mailboxes added. Primary includes online archive.
Secondary account is Exchange 2016 on-prem with cloud archive (hybrid).

Problem:
In primary mailbox (E3 plan) when receiving email from a single address "JaneD@domain.tld" the displayname is incorrect. When composing a new email and typing the incorrect name the email address: JaneD@domain.tld appears under "Other Suggestions" with no "X" option to delete.

Attempted solutions:
I have searched OAB,GAL, every contacts folder loaded in Outlook for the offending entry to no avail.
I have created a contact for JaneD@domain.tld with the correct name. All to no avail.
I have edited the NK2 file searching for JaneD@domain.tld - the displayname field was correct.
I have searched the user list in O365 for any mail contact with the false address.

Any suggestions for tracking this down would be appreciated.

 

[Tim Schoeller]

I found a "Guest Mail User" with the offending address and displayname. Unfortunately I am unable to delete it as yet (greyed out). Will post back with further details.

 

[Tim Schoeller]

Deleted the guest user from Azure AD by searching for JaneD@domain.tld. I suppose the lesson is that these Guest Mail Users will trump your contacts list, the displayname in the email header and just about anything else. Hope this helps someone.

One possible reason why the displayname was incorrect is that JaneD had added an email alias for the user listed in the displayname field after the mailbox was disabled. It is still unclear when a "Guest Mail User" is created but it is now solved.

 

[Diane Poremsky]

I suppose the lesson is that these Guest Mail Users will trump your contacts list, the displayname in the email header and just about anything else. Hope this helps someone.

Yeah... the AD (and GAL) trumps anything in the contact list.

It is still unclear when a "Guest Mail User" is created but it is now solved.

it was probably done automatically when the mailbox was disabled - anything the account previously uploaded to sharepoint or commented on would exist after the mailbox was disabled and the account no longer an official account.