Why are my emails failing with an "Authentication unsuccessful" error?

Version 1

    Do you see your emails in Failed Delivery with the following message?2016-05-20 at 7.44 AM.png

    This means that we were unable to authenticate the connection to your SMTP server.  Most likely, your password had changes recently and you just need to authenticate your new credentials.

    To do this, go to your SMTP Settings where you should see the same error message:

    2016-05-20 at 7.54 AM.png

    Update your credentials and hit Authenticate and Save to see a confirmation message:

    2016-05-20_at_8.00_am.png

    Then, go into your Failed Deliveries to try resending those emails.  If you continue run into trouble, please submit a support request here.