If you have the chance of having a desktop or server somewhere that has SSH enabled, you might want to look at using SSH to tunnel your SMTP traffic even when you are on a foreign internet connection like in a hotel.
I recently traveled accross the US, and in each hotel which provided high speed wired or wireless access, SMTP outbound was blocked. But after connecting back to one of my linux servers via SSG and mapping the public IP address of my various SMTP servers, I was able to successfully send emails. Somehow SSH(port 22) does not seem to be blocked, which is a blessing since it provides encryption for the data that goes through that tunnel and allows remote mapping (like map on localhost a specific IP/port)
In short, if you have the chance of having an OS X desktop/server at the office or home, while on the road make sure you can SSH to it, so that you can access pretty much any port through this SSH tunnel.