Remove invalid emails

[abbasidaniyal]

Set active=False for email address that do not exist. This would reduce celery worker load.

[zrthxn]

For some reason, neither EmailMessage() nor send_mail() (from django.core.mail) return any exception when the recipient is invalid or "not found". The docs say it should, raise an exception when the fail_silently is False, which I've tried many times.

The exception is supposed to be smtplib.SMTPRecipientsRefused or even an int but that doesnt happen. The function succeeds and the success page is rendered without the user even knowing that they typed their email incorrectly.

Even though the SMTP response from gmail (which you can see in the bounce back email) is 550.

550 5.1.1 The email account that you tried to reach does not exist. 
Please try double-checking the recipient's email address for typos or unnecessary spaces. 
Learn more at https://support.google.com/mail/?p=NoSuchUser m19sor1245691pgk.42 - gsmtp

Also apparently we cannot check if the email was invalid by checking if the welcome mail was sent correctly. There is no way to know if an email was actually received.