Returned emails from Outlook

This is the Email Security Gateway at host BARR22.dsdmail.net.

I'm sorry to inform you that the message below could not be delivered.
When delivery was attempted, the following error was returned.


<*** Email address is removed for privacy ***>: host 163.6.2.18[163.6.2.18] said: 554 5.6.0 Invalid
message content (in reply to end of DATA command)
AND THIS ONE:
Delivery Status Notification (Failure)‏
Delivery Status Notification (Failure)
Mail Delivery System (*** Email address is removed for privacy ***)
 
Add to contacts
 
 
2:42 PM
 
 
To: sg****@grappleskinz.com
From:
 Mail
 Delivery System (*** Email address is removed for privacy ***)
Sent:
Tue 8/23/16 2:42 PM
To:
sg******@grappleskinz.com
1
 attachment | Download all as zip (10.3 KB)
GRAPPLESKINZ
 SINGLET ORDER.eml (10.0 KB)
Parts
 of this message have been blocked for your safety.
Show content|I
 trust *** Email address is removed for privacy ***. Always show content.
The following message to <m***.r*********@besd.net> was undeliverable.
The reason for the problem:
5.3.0 - Other mail system problem 554-'5.6.0 Invalid message content'

--Forwarded Message Attachment--
From: sg******@grappleskinz.com
To: m***.r*********@besd.net
Subject: GRAPPLESKINZ SINGLET ORDER
Date: Tue, 23 Aug 2016 14:41:08 -0700
THIS TOO:
Warning: message 1bbt9S-0004qe-Sn delayed 24 hours‏
Warning: message 1bbt9S-0004qe-Sn delayed 24 hours
Mail Delivery System (*** Email address is removed for privacy ***)
 
Add to contacts
 
12:07 PM
 
 
To: sg******@grappleskinz.com
This message was created automatically by mail delivery software.
A message that you sent has not yet been delivered to one or more of its
recipients after more than 24 hours on the queue on web.websharx.org.

The message identifier is: 1bbt9S-0004qe-Sn
The subject of the message is: GRAPPLESKINZ SINGLET ORDER
The date of the message is: Mon, 22 Aug 2016 10:36:40 -0700

The address to which the message has not yet been delivered is:

ja*******@clearwire.net
host clearwire.net [67.222.21.222]
Delay reason: SMTP error from remote mail server after initial connection:
421 Too many concurrent SMTP connections; please try again later.

No action is required on your part. Delivery attempts will continue for
some time, and this warning may be repeated at intervals if the message
remains undelivered. Eventually the mail delivery software will give up,
and when that happens, the message will be returned to you.
***Personal information deleted by the moderator. Please see the Microsoft Community Frequently Asked Questions for more information on how you can protect your privacy.***