Do you block any of the smtp ports for your vps solutions?

I would like to set up a discourse server where a local community can talk to each other. It does need access to an SMTP server for the purposes of account registration, password recovery and forum notifications. I don't want to use a separate service for this and want to set up a small smtp server on the box for that.

Do you block any of the standard (or extended) smtp ports: (25, 2525, 587,465) or any of the pop ports (110, 995 etc)?