At FrOSCon we had nicely fast and stable wifi - but outgoing SMTP connections on port 25 got blocked. An easy way to tunnel out those connections is using SSH's port forwarding feature:
ssh -L 25:localhost:25 firstname.lastname@example.org
With that, you can connect to your local port 25 which gets forwarded via SSH to port 25 on example.org. All you need is an SSH account on that machine. When setting the local port to > 1024, you don't even need local root access.