Mail sent using Gmail Fails

Mail sent using Gmail Fails

I haven't found a solution here for this email sending error, here are the details:
  • I have a Zoho Account marc@silvermarc.com
  • I use Gmail as my "main" email location for viewing and sending email.
  • Zoho correctly forwards all incoming email to my gmail account.
  • But when I send out from gmail using marc@silvermarc.com as the sending address, I get this bounce:
  • Google tried to deliver your message, but it was rejected by the relay smtp.zoho.com [165.254.168.48].
The error that the other server returned was:
535 Authentication Failed
(SMTP AUTH failed with the remote server)

Specific instructions on how to correct this would be happily appreciated!

--Marc