I've occasionally had problems getting my Mail.app settings to work with Rogers too. I end up fiddling with it long enough that it eventually just starts working again and I never know what I did right or wrong.
I can give you my email settings, though ... maybe that will help you.
Mail > Preferences > Accounts
Select an account (or create one with the "+" button (in the bottom left corner).
Account Type: POP
Email Address: firstname.lastname@example.org
Full Name: Firstname Lastname
Incoming Mail Server: www.mydomain.ca
(note: I have my own domain hosted, so I have my own POP server; I'm guessing you put the rogers POP server here)
(I'm guessing you put your rogers email address here)
Password: mypassword (I'm guessing you put your rogers email password here)
Outgoing Mail Server (SMTP): rogers (see below)
Use only this server: Checked
The "rogers" SMTP server settings look like this:
Account Information tab:
Server Name: smtp.broadband.rogers.com
Use default ports (25, 465, 587): selected
User custom port: blank and not selected
Use Secure Sockets Layer (SSL): checked
User Name: email@example.com
(which is my Rogers email address)
Password: abc123 (which is my Rogers email password)
That's it. Hope this helps.