A quick reminder (as even if mail migration seems easy, it always take some time to complete), Exchange 2010 is reaching his end of life in January 14th, 2020
This means there will be no longer technical support, bug or security fixes.
If you still have Exchange 2010 in production and do not have yet started for migration (to either Exchange 2016/2019 or Exchange Online), please start immediately
Microsoft is providing a dedicated page for the Exchange 2010 end of life/end of support here https://aka.ms/Exchange2010EndOfSupport
By the way this end of life/end of support also includes Office 2010 products (Lync, Office client or SharePoint)