Forum Discussion
LRingh_55740
May 24, 2011Nimbostratus
Posted By hoolio on 01/05/2011 02:20 PM
I think SMTP does support X- like headers like HTTP does though. Here is an example of how to do it using .NET:
Just to complete this old thread:
X-headers in smtp messages are any non-standard header that the MUA (client, as in Outlook express och Thunderbird) or MTA (mail server, as in MS Exchange, Postfix or sendmail) wishes to add to the e-mail for any reason. Self promotion is not uncommon, neither is information about anti-spam and/or anti-virus precautions taken when receiving the message.
But an X-header is only a part of the message body, and the message body is usually not available to the receiving server during the conversation where it's decided if access should be granted or not, so simply put: It can't be used.
And second: Since it would be extremely easy to forge such a header they would not be of any practical use to a mail server admin anyway.