On GW 12.0.2 I have a user that when an email is sent to them and if Refresh is not performed, it takes approximately 8 min to display in the Mailbox.
Anytime F5 is pressed the mail displays and it does show the message as arriving at a reasonable time (usually Under 1 min of sending)
The issue is it is Not automatically showing on the Client unless F5 is pressed or wait 8 minutes or more.
I checked Environment, the Refresh interval is 1 min.