The mystery has been solved. The subject emails were not in fact sent through our smtp host but originated from a web application running on a host that is not listed as authorised in our spf. That was the real reason the person reporting the error could not provide me with a copy of their original message, which they cleverly managed to conceal until pressed on the issue this morning.
They also resent the same messages manually through our proper mail server immediately after the transmission failures. So, there were entries in our mail host logs that corresponded to the approximate time that the error messages were generated but which showed no transmission errors. The offending web application is now configured to send through our public mail server. Thanks for all the help. It was an educational experience. Hopefully not to be repeated but valuable none-the-less. -- *** E-Mail is NOT a SECURE channel *** James B. Byrne mailto:byrn...@harte-lyne.ca Harte & Lyne Limited http://www.harte-lyne.ca 9 Brockley Drive vox: +1 905 561 1241 Hamilton, Ontario fax: +1 905 561 0757 Canada L8E 3C3
