client does not have permission to send at this sender (550)

0 votes
asked May 12, 2011 by Enrico (370 points)
edited Jul 4, 2012

Hi, i using smtp class to send a mail but the method send return an exception.

The message is: client does not have permission to send at this sender (550)

this the call stack:

in Rebex.Net.Smtp.COvOkZ(String , String )
in Rebex.Net.Smtp.bUTESW(String , String[] , String , Stream )
in Rebex.Net.Smtp.BTPxIKZ(MimeMessage , Stream , MailAddress , MailAddressCollection )
in Rebex.Net.Smtp.Send(MailMessage mail, String sender, String recipients)
in Rebex.Net.Smtp.Send(MailMessage mail)

If configured the same mail with outlook and i don't have the same problem.

Best regards Enrico

Applies to: Rebex Secure Mail
commented May 12, 2011 by Jan Sotola (17,670 points)
edited May 12, 2011

Could you create a communication log produced using the Smtp object's LogWriter property ( as described at ). You can post the log here or send it us to e-mail

1 Answer

0 votes
answered May 24, 2011 by Lukas Pokorny (128,250 points)
edited May 24, 2011

This seems to be the Microsoft Exchange's 'Client does not have permission to send as this sender' error message. The most likely cause is that you used a From address in your message that was different from the e-mail address assigned to the authenticated user in Exchange. Using the same From address used in Outlook should solve the problem.

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