iTunes won't sync email accounts to iPhone after adding Mobile Me account

MobileMe will sync e-mails so you don't need iTunes to do it as well. In fact, having both may confuse the sync process. Once set up on your iPhone, other non-MobileMe IMAP e-mail accounts should also be syncing over the air.

If you really need to use iTunes to sync mail for some reason, first turn off Mail in the settings for your MobileMe account on your iPhone (Settings, Mail Contacts Calendars, MobileMe).

What can be selected under the Info tab for your iPhone sync prefereces with iTunes for an email account or accounts is for transferring the email account settings only from your computer to your iPhone so you don't have to manually create the account with the iPhone's Mail app. This only needs to be selected once. After the email account settings have been transferred to your iPhone, this can be deselected. This does not have to remain selected since there is nothing gained and no benefit with leaving this selected.