We have a number of users who are using wifi hotspots etc to send emails from various devices and keep running into issues with many ISPs of port 25 blocking. I saw this:
SMTP Submission Port
Which is a little old though possibly valid but after the changes since those days I wondered if anyone has a better/more recent solution for this? I don't want to lose port 25 for submission for those that use it successfully but I wanted to offer an in-house solution for these mobile users.