Symptoms
After you send many email messages by using SQL Server 2016 Database Mail, your CPU usage is higher than expected.
Cause
This issue occurs because Database Mail creates an orphan System.Timers.Timer object in every loop iteration of the queue processor.
Resolution
This issue is fixed in the following cumulative updates for SQL Server:Cumulative Update 2 for SQL Server 2016 SP1Cumulative Update 4 for SQL Server 2016
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:Latest cumulative update for SQL Server 2016
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminologythat Microsoft uses to describe software updates.