No, it's not a proxy issue at all. Usually most ISP do block all smtp access but their own. However -- note it is a SSL connection on 110 that you are tring to use and not un-secure smtp over port 25 (Yes, I am a smtp guru).
Port 25 blocked, and 110 sometime. The secure port you changed to is rarely blocked due to by standard it required authentication to use, and is unlikely to be spam.
Sending and receiving email are two completely different things. Normally the POP and IMAP ports are never blocked by the ISP, and you shouldn't need to change them.
Options, from easiest to hardest -- use Webmail (sounds like you don't have it as it is your own domain), use SSL (secure) services for both SMTP and IMAP, You could setup a VPN back to a "home" system, or even just use putty/ssh to create a temporary tunnel from a location that you can get to your SMTP server.
Or course, you can always find your IP address, check it against ARNIS Whois database to see who own the IP range, then lookup their smtp server.
telus == smtp.telus.net
shaw smtp.shaw.ca
disclaimer: Yes, I admin a lot of large SMTP servers
