Suddenly getting 550 error "no such user here"
Problem reported by John Millet - 2/4/2015 at 1:39 PM
Today, I suddenly started getting error messages when sending mail to my user accounts. Some messages go though and some get rejected. The rejection message is 550 5.1.1 no such user here". But it is totally random as to which user it happens to and when it happens.
In fact, I can't even send a message to myself when I am already logged in as myself. I get the same error message in the log, but I do not get the undeliverable message in my email as I would if I was sending it from outside my domain.

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Employee Replied
Employee Post
Hello John,
Thanks for the information and submitting a Support Ticket. I do believe you have resolved this issue with your provider. There was a spam filter in place that was rejecting the messages after a specific amount of failed attempts by the IP.
Please let us know if you have any other questions.
Thank You.
Russ Michaels Replied
hi, did you find the cause of this, I am having same issue. The web server is actually set as authentication bypass on the mail server, so should never get blocked, but still emails are randomly being rejected with "no such user"
Yad Rashid Replied
We have the same issue , have you fixed the problem ?
Pablo Carrau Replied
We're suddenly experiencing the same issue as well. Is there a resolution for this??
Sérgio Rocha Replied
We're experiencing the same issue as well, we use a Incoming SM gateway, I was wondering if it was a problem of the gateway webservice request, but i looks that its a different problem.
The problem start before the last upgrade, in fact we upgrade to last version to try stop this problem.

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