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Undelivered Mail: 501 Syntax error in parameters or arguments

Tolik

Hello everybody,

we send and receive mail via sophos central
We have been receiving the following message more and more frequently for about 1 week:

"host ***** refused to talk to me: 501 Syntax error in parameters or arguments"

The message does not only come from a recipient/host. Other senders can then successfully deliver to this recipient/host.

In the last report, we have now found out that it was sent by a sophos node that is on a blacklist. but then should the error message look different?

 

best regards

Tolik



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  • 0

    Hi  

    Are you able to send Emails to other servers without any issues? The error 501 mostly occurs due to an invalid email address, but it can also be associated with connection problems sometimes.

    Regards

    Jaydeep

  • 0 in reply to Jaydeep 
    Hi there,

Yes, I can send to others.

It is strange that one colleague can send to this address and the other receives 501 errors. 

    And at some point the colleague can also send the error 501 to the recipient. The error has been around for about 1 week. Before this did not come ...
  • 0 in reply to Tolik

    Hi  

    That does not seem to be an issue from Central to be honest. Are you still seeing the NDR emails?

    Regards

    Jaydeep

  • 0 in reply to Jaydeep

    Hi all,

    We do face the same issue of 501 error.

    At least once a day ( 3000+ Mails/day out are fine) we receive an error like:  host mail.xxx.yyy [134.93.xxx.yyy] refused to talk to me: 501 Syntax error in parameters or arguments

     

    I was wondering about the subject :  date:subject:to:from;

    within the error report message.

     

    I did check reputation of domain/IP, BL, MX etc. but no issues found.

     

    Any help or info more then appreciated

     

Reply
  • 0 in reply to Jaydeep

    Hi all,

    We do face the same issue of 501 error.

    At least once a day ( 3000+ Mails/day out are fine) we receive an error like:  host mail.xxx.yyy [134.93.xxx.yyy] refused to talk to me: 501 Syntax error in parameters or arguments

     

    I was wondering about the subject :  date:subject:to:from;

    within the error report message.

     

    I did check reputation of domain/IP, BL, MX etc. but no issues found.

     

    Any help or info more then appreciated

     

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