Hi.
In our organization there are two exchange forests - 2010 and 2013, there is a trust between them, exchange server 2010 is maintaining the mail flow in domain A, exchange server 2013 is maintaining the mail flow in domain B. Some of the users have domain and mail accounts in both domains, their computers are joined in domain A, as well as their primary mail accounts are set on exchange server 2010, auto-discover is working fine . Recently, a colleague complained that on his Outlook 2016 he is prompted to enter the password for the secondary mail account (from domain B). All attempts to authenticate has failed, outlook does not accept the password anymore, the colleague wasn't change its password. Just to mention that no settings were changed at the server side, no updates were applied on the server and the workstation. The curious fact is, that the user is managing to authenticate in OWA, as well as on his mobile device. I have tried to setup his account on a test workstation, outlook does not accept the password. On the same test workstation I have successfully setup a test account, which is located on domain B, where the problem account is located too. Cached credentials are not the reason for this issue, because my colleague does not work on the test workstation. I do not what is going on, the problem account and the test account have the same settings at the server side. Probably the problem account is broken on the server. Does anybody know how to fix the issue?