I had selected Exchange 2016 General Discussion, but the was incorrectly categorized as 2013.
We do a GAL Sync with a partner company. The GAL Sync creates mail enabled contacts and those contacts are available in our GAL. The expected behavior is that when someone from this company sends us an email, and in the header, the From is in this format: Last, First <first.last@company.com>. There will be a reverse lookup done and in the users inbox, the From in the user's inbox is changed to the DisplayName attribute, which in the case of these contacts is "First Last" This is still happening most of the time, but in some cases, and I can't figure out if its consistent with certain senders but I suspect so, the From is displayed as it is in the message header, as Last, First <first.last@company.com> (From what is in the From data in the message header). If I open the email and double click on the name, I can open their contact card info and see their phone number, etc., so the contact is being found, but the name is just displayed as Last, first.
The Displayname in the AD Mail Enabled Contact Objects are correct, and I can't find anything different between the working and non working contacts. This had been working fine for about 8 months. It looks like this started occurring on the 6th of this month. Would anyone know specifically what to look for or how this works in order for me to troubleshoot this?