We just migrated from Exchange 2007 to Exchange 2013 and we have a very strand issue that I can't quite put my finder on. Whenever a specific user is CC'd together with a mail enabled PF in the same email, a 2 minutes delay is introduced only for this user. Before I give you my troubleshooting steps, here are the different test scénarios I tried :
external sender to PF with User1 and User2 CC'd = PF and User2 receive email instantly andUser1 receives email 2 minutes later
external sender to User1 = No delay
external sender to User2 with PF CC'd = No delay
external sender to User1 with PF CC'd = 2 minutes delay on User
The message for User1 get's stuck in the submission queue for 2 minutes with the Error message : Message rerouted and delayed by store driver
Here is a tracking a faulty message where the user was CC'd (User2 is set to forward email to externalcontact, you can ignore that) :
Any help at this point would be greatly appreciated.