Email server on OS 10.12.6 with 60 email accounts has been in operation for over a year with virtually no issues. Over the last month, have observed "Postfix mail transport not available" errors both sending (SMTP) and receiving (IMAP). I have adopted the practice of restarting MAC twice per day just to minimize the problems. The consultant that installed the server is no longer available and I have been unable to get problem resolved using Apple Care. Is anyone available to debug my system? I am in Dallas Texas, but believe I can provide screen sharing capability if someone is willing to try.