can't send anymore photos via iPhoto The email server didn’t recognize your username/password combination.

Go into iPhoto's Accounts preference pane and remove the email account. Close iPhoto, reopen and add the account back.

A better option in my opinion is to set Mail as the email client for iPhoto in iPhoto's General preference pane. Mail will give you a sent copy automatically, better access to your Contacts, also has templates in its Stationary section and is more efficient.