Regardless of the mailserver, it's the boss, if it does not permit tracking it will never work.
Which is good by the way, personal opinion, it just creates overhead and most people turn off the receipt delivery any way, as they should.
Before you wonder why:
Let's say a spammer sends a tracked message, if he gets the delivery, he knows the server exists, and maybe the user. If he receives a read receipt, he KNOWS the user exist.. BINGO, you're on the list for sure. If the solution is here, let us know it was helpful so others can benefit from it as too