Using Outlook 2003 client using pop3/smtp to an exchange server over a particular internet connection the SMTP send process fails with the following error detected through protocol tracing:
SMTP Reply Code: 451, Message: SMTP S
451 = Requested Action Aborted: Local processing error
The error that occurs on the client is a generic one with no hits on mskb or web.
Using a secondary Internet connection the SMTP process completes no problem, using the same client. When the process completes, the SMTP reply code is 250.
Good:
Client - smtp data
Server - reply code: 334
Client - smtp data
Server - reply code: 235
Client - smtp mail from
Server - reply code: 250
Bad:
Client - smtp data
Server - reply code: 334
Client - smtp data
Server - reply code: 235
Client - smtp mail from
Server - reply code: 451 SMTP S
connection closed
The problem is not just one client, but all at the site that is having the problem. When all go through the default Internet connection, they all fail, when they all go through an alternate connection, they all succeed.
So one would think its a problem with the ISP or network which is the default route or primary internet connection. Well there is not a connection or session failure, the abort is coming from the Exchange server itself.
Maybe there is a spam or rbl filter that is detecting the source IP as a threat and this is how it is closing the SMTP session? I have seen others that have mentioned an inline filter such as a PIX or hardware device or software firewall inspecting SMTP packets but I do not see a protocol flow issue.
My issue is I do not have direct access to the Exchange server to perform direct testing on it or to review advanced logging.
Has anyone seen a 451 SMTP S abort and know what the "local processing error" could be on the Exchange server? I am suspecting an RBL or Spam filter myself.
Thank you in advance
Jason Stevens
SMTP Reply Code: 451, Message: SMTP S
451 = Requested Action Aborted: Local processing error
The error that occurs on the client is a generic one with no hits on mskb or web.
Using a secondary Internet connection the SMTP process completes no problem, using the same client. When the process completes, the SMTP reply code is 250.
Good:
Client - smtp data
Server - reply code: 334
Client - smtp data
Server - reply code: 235
Client - smtp mail from
Server - reply code: 250
Bad:
Client - smtp data
Server - reply code: 334
Client - smtp data
Server - reply code: 235
Client - smtp mail from
Server - reply code: 451 SMTP S
connection closed
The problem is not just one client, but all at the site that is having the problem. When all go through the default Internet connection, they all fail, when they all go through an alternate connection, they all succeed.
So one would think its a problem with the ISP or network which is the default route or primary internet connection. Well there is not a connection or session failure, the abort is coming from the Exchange server itself.
Maybe there is a spam or rbl filter that is detecting the source IP as a threat and this is how it is closing the SMTP session? I have seen others that have mentioned an inline filter such as a PIX or hardware device or software firewall inspecting SMTP packets but I do not see a protocol flow issue.
My issue is I do not have direct access to the Exchange server to perform direct testing on it or to review advanced logging.
Has anyone seen a 451 SMTP S abort and know what the "local processing error" could be on the Exchange server? I am suspecting an RBL or Spam filter myself.
Thank you in advance
Jason Stevens
