We have also enabled port 26 for SMTP. What this means is that you should be able to continue using mail.yourdomain.com for your SMTP setting, however, you need to change the default port from port 25 to port 26. Often times this setup is more convenient, especially for laptop users who travel a lot. It means you will not have to change your SMTP every time you you travel and use another ISP.
When helping people with their email accounts it's always a bit of a challenge to determine their ISP never mind their smtp server. Searching the knowledge base I found this that should help others. Worked great for my lap top, as verizon's wireless leaves alot to be desired in that area.

Thanks MATT!