Since updating to OS 15 and UI 7 the email time period to sync messages for Exchange onpremise has been reduced to 1 day. I can only see messages received in the last 24hours, this is on the Samsung email app and Outlook. Outlook inbox on my PC shows messages going back several years. Samsung email app had time period set to all time, flip flop that to 30 days/1 month and it didn't make a difference.
