Since I installed Snow Leopard, the Mail application asks for my login password every time I check for new messages. I haven’t found a preference that will let me have Mail automatically without using the keychain passwords. Is there a way?
Ron Sharp

What you’re describing isn’t normal, so I wouldn’t spend time hunting around in Mail’s preferences. First, ensure you’re entering the correct password. One way to confirm that is to log on to your ISP’s Webmail host and retrieve your email. If the password works there, you know it’s good. So if that’s not the issue, you probably have a problem with the keychain where your email password is stored (if you’re asked to enter a password – meaning sometimes yes, sometimes no – then there may be a problem on your ISP’s end).

Open Keychain Access (within the /Applications/Utilities folder). Choose Keychain First Aid from the Keychain Access menu. In the resulting window, enter your administrator’s password, enable the Verify option, and click Start. With luck, red entries will appear in the window, indicating that there’s a problem with your keychain. Now enable the Repair option and click Start. With the same measure of luck, those keychain problems will be repaired and Mail will no longer harangue you for a password.

If Mail continues to hound you, you could try deleting and recreating the account. Before you do that, select the account in Mail’s Mailboxes list, hold down the Control key, and click on the account’s Inbox. Choose Archive Mailbox from the menu that appears and choose a place to save your archive when prompted. This ensures that the messages for the account aren’t vaporised when you delete the account. Ditto for the account’s Sent messages if you keep such things.

Now, go to Mail > Preferences > Accounts, select the troublesome account in the Accounts list, and click the minus sign (–) button to delete the account. Click the plus sign (+) button and recreate the account.