"Automatically checking email" preference doesn't work?

Question

I'm in the midst of switching ISPs. Right now I have 2 ISPs with 2 different connections (one dial-up, one DSL). The dial-up ISP, as expected, cannot connect to the mail server over the DSL connection, so under Mail Preferences I've unchecked "Include when automatically checking for new email" on that account.
However, Mail continues to try to connect to the dial-up's mail server whenever launched or whenever I check for new email. Since it can never connect it hangs for several minutes attempting to complete this connection before coming up with an error message.
How do I get this preference to work properly? I need to have both email accounts available for the next month or two while making sure all contacts are using the new email address, so I can't simply disable the old email account under preferences, as then it no longer shows up at all. What I need is to have the account enabled, but only to check for new email when given instructions manually to do so.
Thanks
Powermac 2x2.5   Mac OS X (10.4)  

Answer 1

This doesn't answer the question regarding the problem with automatically checking for new mail but connecting to the dial-up ISP should not be required to check the dial-up account's incoming mail server for new mail. This can be done when connected to the internet with the DSL connection.
I still have an Earthlink dial-up account for use when traveling if a high speed wired or wireless connection isn't available but I primarily use a high speed cable modem internet access when at Home. I access my Earthlink dial-up account with the Mail.app when connected at Home without any problems and without being prompted to access Earthlink via a dial-up connection when the account is checked for new mail.
You can turn off automatically connect when needed under the PPP options for your internal modem network configuration or disable to internal modem as an access point via System Preferences > Network if you are using the DSL connection only and you can include the dial-up account to automatically check for new mail.