iCheckMail is a new application that will allow you to set the time interval between checking for new mail.
When you start the app all you have to enter is the value in minutes. When you enter 0 the app won’t check automatically. So that means you will need to check your mail manually.

1) Before you install the app, make sure you install Erica’s Utilities.

2) Locate and install the app.

3) Run the app and set your mail fetching time.

This little app is available in the Installer.app through the Big Boss packaging source, see our sources page.