I've had this error in the past and was able to fix it via the Live Chat. Unfortunately, for the past few days I've not been able to connect to the live chat (my internet connection is fine, it's an error with Pegg I think). Either way, this error is popping up again even though I've already entered the SMPT port and address manually. Please advise on how to fix this, being able to email invoices is incredibly important. Unfortunately, if this issue persists with no solution, we'll have to look into something a bit more modern like QuickBooks.