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Hello Experts 
 
I'm working on trouble tickets in my company and ran across one that I'm not sure about solving. &nbsp;My user didn't tell me which mail program was used, so I listed them both. &nbsp;I know my company sends out large amounts of email through PowerMTA and I thought maybe we were blacklisted or something, but can't find anything that would support that idea. 
 
So, what do you guys think? &nbsp;Is this something on my server end or the receiving end? &nbsp;My diagnostic info is..... 
 
Your message has encountered delivery problems 
to the following recipient(s): 
email@domain.com 
Delivery failed 
421 Service Temporarily Unavailable 
No recipients were successfully delivered to. 
Reporting-MTA: smtp.domain.com 
Received-From-MTA: dns; domain.com (unverified [x.x.x.x]) 
Arrival-Date: Fri, 25 Mar 2011 14:56:35 -0400 
 
Final-Recipient: rfc822; email@domain.com 
Action: failed 
Status: 5.4.7 (Permanent failure - routing/network: delivery time 
expired) 
Remote-MTA: dns; cluster4a.us.messagelabs.com (is this some spam agency's dns?) 
Diagnostic-Code: smtp; 421 Service Temporarily Unavailable 
 
Any help would be greatly appreciated. 
 
Thanks.
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Hello Experts

I'm working on trouble tickets in my company and ran across one that I'm not sure about solving.  My user didn't tell me which mail program was used, so I listed them both.  I know my company sends out large amounts of email through PowerMTA and I thought maybe we were blacklisted or something, but can't find anything that would support that idea.

So, what do you guys think?  Is this something on my server end or the receiving end?  My diagnostic info is.....

Your message has encountered delivery problems
to the following recipient(s):
email@domain.com
Delivery failed
421 Service Temporarily Unavailable
No recipients were successfully delivered to.
Reporting-MTA: smtp.domain.com
Received-From-MTA: dns; domain.com (unverified [x.x.x.x])
Arrival-Date: Fri, 25 Mar 2011 14:56:35 -0400

Final-Recipient: rfc822; email@domain.com
Action: failed
Status: 5.4.7 (Permanent failure - routing/network: delivery time
expired)
Remote-MTA: dns; cluster4a.us.messagelabs.com (is this some spam agency's dns?)
Diagnostic-Code: smtp; 421 Service Temporarily Unavailable

Any help would be greatly appreciated.

Thanks.

421 Service Temporarily Unavailable

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.

Email Servers

Software is any set of instructions that directs a computer to perform specific tasks or operations. Computer software consists of programs, libraries and related non-executable data (such as documentation). Computer software is non-tangible, contrasted with computer hardware, which is the physical component of computers. Software written in a machine language is known as "machine code". However, in practice, software is usually written in high-level programming languages than machine language. High-level languages are translated into machine language using a compiler or interpreter or a combination of the two.