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451 4.4.1 [internal] No valid hosts (unable to make any connections)

Created: 03 Nov 2010 • Updated: 07 Nov 2010 | 4 comments
prasad.ganta's picture
This issue has been solved. See solution.

We are using SBG 9.0.0-20.We have these messages(actions) in the delivery queue for a particular domain.

451 4.4.1 [internal] No valid hosts (unable to make any connections)

Actually what does this error represent...?

Thanks in Advance...

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talecue's picture

I think SBG can't communication remote mail server.

You can check it connect to SBG by ssh and telnet remote server
Port 25.

Cricket17's picture

To figure out if it's you, or the recipient domain, take a look at Put in the recipient domain.  You'll get back a list of their MX hosts.  You can click SMTP Test for each host to check out it's status via the mxtoolbox servers.

prasad.ganta's picture

I have done SMTP test at the site provided with the remote server as the the mails are stuck in the delivery Queue, it is showing this message

No connection could be made because the target machine actively refused it X.X.X.X:25

Is this because of having authentication for remote server at SMTP?

prasad.ganta's picture

All the mails of that doamin are moved from delivery queue.I think there is a problem with their end.

That tool( is really helpful..

Thanks for all the replies..