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One of our users has been sending emails to a particular client with no problem for the last year. Suddenly, today, he started receiving Undeliverable - 554 Transaction Failed messages for some of the emails; however, some are still getting through. For example, he sent one test message to two users at the client office; I checked our outgoing Barracuda box and one of the messages has a status of Delivered; the other has a status of Rejected.

Any idea what could be causing this? Is it likely on their end or ours? It seems the messages are going out fine from our end, but should I be checking something else?

Thanks in advance.

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Any more details on the message that was rejected? Is there a log on the Barracuda you can look at for more details? – joeqwerty Aug 10 '10 at 18:17
Yes, but the log says that no reason was given for the rejection. – johnnyb10 Aug 10 '10 at 18:57
Was this ever resolved? Having a similar issue – Sherif Buzz Feb 7 at 23:02
up vote 2 down vote accepted

I would suggest collecting a packet capture of the SMTP session. That would tell you:

  • Where exactly in the conversation the error is coming up.
  • The specific error response the server is generating.
  • (Hopefully) the specific server name on the recipient side.

You can use this information to request help from the recipient side in troubleshooting.


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E-mail can be rather finicky. I would first check blacklists to ensure your IP has not been blacklisted. Another sign that you may have been blacklisted is that mail is only being blocked to certain domains i.e. hotmail. You could also follow the steps outlined here to try and ensure that your email is delivered properly.

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