420 TCP write error

hi Experts,

Groupwise GWIA version: 6.5.7
Platform: Netware 5.1

Received non-deliverable error for outbound email to partner's internet domain...Other internet domains were ok. Inbound email from partner's internet domain were ok.

Transcript of session follows:
        Command:  Data...
        Response: 420 TCP write error

I have done a search on google and read thru the following links. Done a spamhaus check to ascertain that our outbound smtp public ip was not blacklisted.  

Done a telnet to partner's internet domain and returned a  "Connect failed" (presumably they have blocked any incoming telnet to their SMTP gateway)

Please advise further troubleshooting steps to identify cause of non-deliverable emails to only certain internet domains.

Who is Participating?
deroodeConnect With a Mentor Systems AdministratorCommented:
C:\TEMP>nslookup -query=mx stellatravel.co.uk
Server:  mailgate.eur.nl

Non-authoritative answer:
stellatravel.co.uk      MX preference = 10, mail exchanger = relay1.netnames.net
stellatravel.co.uk      MX preference = 100, mail exchanger = relay2.netnames.net
stellatravel.co.uk      MX preference = 1, mail exchanger = mail.stellatravel.co.uk

C:\TEMP>telnet mail.stellatravel.co.uk 25

220 mail.stellatravel.co.uk Microsoft ESMTP MAIL Service ready at Thu, 8 Sep 2011 08:42:18 +0100

Are you sure you connected to the smtp port?
Please follow the instructions in the previous link...
deroodeSystems AdministratorCommented:
Does all mail to that domain fail?

Can you try telnetting to the SMTP port of the partner's SMTP server? See the following article about troubleshooting SMTP using Telnet.


If you can deliver mail by using Telnet then you have a Groupwise problem. If delivery fails anyway there is something different going on...

You can use Telnet from your Netware server with the following telnet client:

kenny_klbnAuthor Commented:
hi deroode,

Does all mail to that domain fail?
Yes, all mail to that domain failed.

internet domain concerned is stellatravel.co.uk
telnet result to smtp server ie mail.stellatravel.co.uk is "Connect failed"
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