How do you change the IMAP port in Mac Mail?
I am using Mac Sierra Mail to read email on a private email server. That server currently uses port 993 with STARTTLS. It works fine. They are changing their IMAP SSL port from 993 to 939 to slow down hackers. I cannot see how to change the IMAP port in Mac Mail. The SMTP port is a box under Advanced, but the IMAP port is not. Is there a .plist file that can be edited to change this?
MacBook Pro (17-inch Early 2011), OS X Yosemite (10.10.3)