Yes I know this is a lengthy… long… and very specific post title, but I hope it helps someone else in the same predicament.
I have been fighting OS X Server and Verizon FiOS for months. The shortest explanation is that Verizon blocks port 25 (standard SMTP port) and forces you to use port 465 (SMTP via SSL). I’m Ok with that rule, however, no matter how many times I try to use smtp.verizon.net:465 in OS X Server, I would get an error in the /var/log/mail.log stating you must use TLS. When trying to use port 587 to force TLS, I get an operation timeout error. If I switch to use smtp.gmail.com:[25,465,587] I would get black listed b/c Verizon won’t allow SMTP off their FiOS network that does not originate from a verizon SMTP server.
Which leads me to today. I was searching (again) a way to fix this by sending a simple
sendmail [email protected] < filename.txt when I stumbled upon this blog post. The goal of the article is to send TLS mail from postfix on a linux box. While reviewing the commands and comparing to an OS X Server main.cf file (in /Library/Server/Mail/Config/postfix) I noticed a couple key items missing. Unfortunately I took a shotgun approach so I don’t know specifically which line fixed the issue, but here is a copy/paste of the items that I placed at the bottom of my main.cf:
These settings assume that you have configured Mail services to relay to smtp.gmail.com:587 and associated it to a proper Gmail account that can send mail.