Ok, well I've good news and bad news. Our email engine is pretty good, we deliver over 100k invoices a month. So it's probably down to the settings you use. Have you got those settings or a link to them?
The two in bold are coming back as wrong from Apple. I've saved the above settings in your account. I've also deleted my test invoices.
So you'll just need to check your username and password (it's probably your password) and then re-enter them in the Email Settings screen and you should be all set. Let me know how you get on, I can't reset your apple password I'm afraid, but I've put in all the correct settings for you. Hope that helps Anna. Let me know how you get on. Pete