You may come across the scenarios to perform migration from Exchange 2003 to 2013, from Exchange 2007 to 2016, and also  from Exchange 2010 to Exchange 2019. 

It become tedious to perform migration in such  scenarios as those Exchange Servers cannot coexist within the same Active Directory forest.  So it requires below steps

 You need to  migrate data to the Exchange  server  which  coexists with the target Server. Now you need to  decommission the earlier one.
Now you need to migrate the data to target  server and decommission the intermediate server .
EdbMails for the Migration from legacy Exchange directly to Exchange 2019 or 2016

EdbMails  Exchange migration tool helps to perform migration of mailboxes  from Exchange 2003 to 2013, from Exchange 2007 to 2016, and also  from Exchange 2010 to Exchange 2019. directly without any intermediate step , ensuring zero downtime. This will reduces your effort and saves precious time.

Know More: Exchange Migration