550 Mailbox not found (user unknown). 10.2 Server.

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Level 4

1,505 points

550 Mailbox not found (user unknown). 10.2 Server.

I am getting a lot of the following errors in non-delivery reports when sending mail. The message claims to be from postmaster@mydomain, but I relay through mail.btconnect.com, is the message originating there or from my server?

Could not deliver message (ID=2935781) to remote account 'user@hotmail.com'.
Remote server returned error: 550 Mailbox not found (user unknown).

All users authenticate with my SMTP server.

James

Posted on Oct 9, 2005 5:24 PM

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Answer 1

Oct 11, 2005 12:39 AM in response to James Dicken

Hi

The 550 error indicates that theuser no longer exists on the destination mail server -

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Answer 2

Long Lane

Level 1

105 points

Oct 11, 2005 5:12 PM in response to James Dicken

Question: why do you relay through mail.btconnect.com? I use btconnect as well, but I have my own server acting as smtp sender. It works perfectly. Did BT manage to give you a real reverse DNS, ie. one which points to your domain?

And last but not least: 10.2 is not considered save any longer and there are no more security updates. If you can spend the money, I would upgrade to at least 10.3.9

Hope this helps

Lane

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Answer 3

James Dicken Author

Level 4

1,505 points

Oct 12, 2005 8:29 AM in response to gabriel blazquez

Not necessarily.

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Answer 4

James Dicken Author

Level 4

1,505 points

Oct 12, 2005 8:32 AM in response to Long Lane

Lane

The problem with upgrading would be the large amount of manual stuff I have on the server, such as squid etc. I have spent ages customising it and to upgrade it would take such a long time im not sure if its worth the downtime. I am considering setting up the new one in parallel with the old then switching, but that is a huge faff too!

BT never did give me the proper reverse DNS. OH how I tried! I must have made at least 20 phone calls to people of varying competence and willingness to help and still they refuse. How did you get it?

James

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Answer 5

David_x

Level 4

3,011 points

Oct 13, 2005 4:51 AM in response to James Dicken

James, I'm not sure of your exact question but...

I am getting a lot of the following errors in non-delivery reports when sending mail

So these are non-delivery reports for mail that you know originated from your users?

If you do not know who sent the originals then it is probably just spam which is using your domain name. Unfortunately, all the responses from the 'dead' email addresses being spammed will respond back to you. Just bad luck. It will be someone elses domain name being used next week.

-david

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Answer 6

James Dicken Author

Level 4

1,505 points

Oct 14, 2005 4:27 PM in response to David_x

Im sure the messages are real, and about emails we have tried to send.

Thanks,
James

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Answer 7

Dec 29, 2005 3:28 PM in response to James Dicken

I am also having the exact same issue On 10.2 Server. For some reason all of my users can't email any hotmail accounts but we can receive emails form Hotmail. I am also using SMTP. Any ideas what it could be?

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Answer 8

David_x

Level 4

3,011 points

Jan 17, 2006 9:27 AM in response to vette_red1998

Your server could be blacklisted by Hotmail - I think they are pretty sensitive nowadays. Are you relaying the server smtp out via your ISP or is communication with receiving servers being made direct from your own server?

If the latter, try setting server to relay via your ISP's SMTP server and see if Hotmail accept those. If this works then it will tend to confirm that Hotmail has either blacklisted your server or doesn't like something about the SMTP communication with you.

-david

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