I would verify that their Exchange account is the only account within outlook. From a few different places it looks like it could be something stuck in Drafts too (although you said you checked there). Possibly removing the account and re-adding it in Outlook could be the quick fix to it (although they would lose their saved autocompletion which a lot of people complain when they lose it).
Outlook For Mac Error Code 19874
Im running 2016 on probably 25 Mac's and haven't seen this issue yet, but I have had weird issues with Outlook in general that aren't worth the time messing with and just adding the account back again will fix saving all of our times.
Mac Microsoft Outlook Error Code 19874
It used to be a thing in Outlook 2011 for Mac that if the mailbox was too big, or if there were too many folders it would just freak out. (and always really random when it freaked out!) Repairing the database usually works. This article provides a one-stop solution for users looking to resolve common Outlook errors. Both manual and automated approaches to fix common Outlook bugs are briefly described in above sections. In case of PST corruption, you can use Kernel for Outlook PST Repair for quick results. Watch Video: To know Complete Process of Outlook PST Repair. Solution: Go to the Windows Control Panel Mail Mail Setup option. Click on the Show Profiles Add button. Then, create a new Outlook profile and add your email account to it. Affiliate Disclosure: Some links mentioned below are affiliate links, we may earn some amount if you make a purchase. Outlook for Mac is the tool provided by Microsoft for Apple user’s to use the Outlook application. Even if you are using the latest build of Outlook for Mac, iOS and Android, Groups will only be available to those who have joined or been added to a group. Once we add the ability to create and join groups on Mac, iOS and Android, every Office 365 user will see Groups in Outlook. I'm trying to configure my Microsoft Outlook 2011 MAC email program to send and receive my att.net account. I can't seem to find the configuration information. I tried using the pop.att.yahoo.com port 995 and smtp.att.yahoo.com port 465 configuration as indicated in a previous version of Outlook.