Emails are not sending and are coming back unsent

From: Mail Delivery Subsystem <MAILER-DAEMON@atl4mhob17.myregisteredsite.com> [ add to contacts ]

To: partyplanner@skyhighamusements.com Cc: Date: Thursday, July 23, 2015 01:03 pm Subject: Returned mail: see transcript for detailsAttachments: Text version of this message. (1KB)

(374B)

Hi Carolann, a few details about your SKY HIGH Birthday for 8 year old Sarah (11KB)

The emails we are trying to send through IO are coming back to us unsent. This is the email we see and the customers are not receiving a email.

The original message was received at Thu, 23 Jul 2015 13:03:45 -0400

from [10.30.77.68]

*** ATTENTION ***

This email is being returned to you because the remote server would not

or could not accept the message. The registeredsite servers are just

reporting to you what happened and are not the source of the problem.

The address which was undeliverable is in the section labeled:

"----- The following addresses had permanent fatal errors -----".

The reason your mail is being returned to you is in the section labeled:

"----- Transcript of Session Follows -----".

This section describes the specific reason your e-mail could not be

delivered.

Please direct further questions regarding this message to your e-mail

administrator.

--Registeredsite Postmaster

----- The following addresses had permanent fatal errors -----

<norahmay_03@hotmail.com>

(reason: 550 Requested action not taken: mailbox unavailable)

----- Transcript of session follows -----

... while talking to mx2.hotmail.com.:

>>> DATA

<<< 550 Requested action not taken: mailbox unavailable

550 5.1.1 <norahmay_03@hotmail.com>... User unknown

<<< 503 Need Rcpt command.