Sometimes you'll receive Mail delivery failed messages, this is normal.
This means the activation email (sent to confirm the email address and activate the account) was not accepted by the email server responsible for the email address provided during registration.
Generally these messages should be returned to no-reply@[your domain] we suggest filtering out messages with subject "Mail delivery failed" that are to no-reply@[your domain].
The message will look much like this:
From: Mail Delivery System <[An Email Address, which is us, but never checked]>
To: no-reply@[Your Domain]
Subject: Mail delivery failed: returning message to sender
This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:
[An Email address which is unknown]
SMTP error from remote mail server after RCPT TO:[An Email address which is unknown]:
host [A SMTP Server] [<An IP Address>]: 550 5.1.1 <[The same unknown email address]> Recipient not found. <http://x.co/irbounce>
------ This is a copy of the message, including all the headers. ------
Return-path: <no-reply@[Your Domain]>
Received: from [our server] ([IP])
by [our server] with [Some more text]
(envelope-from <no-reply@[Your Domain]>)
id [some more text]
for [The Same unknown Email Address]; [Date]
Content-Type: text/plain; charset="utf-8"
Subject: [Your Company Name] Website Account Activation
From: "[Your Company Name]" <no-reply@[Your Domain]>
To: [The Same unknown Email Address]
Message-ID: <[Looks like an email address, but isn't]>
Reply-To: [Your Name] <[Your Email]>
Your [Your Company Name] website account has been successfully created. To confirm and activate your account, follow the link below within 3 days:
If you did not make this request, you can safely ignore this message.
The [Your Company Name] Team