5 thoughts on “Random thought of the day

  1. My point exactly. :)

    The Sender header is the entity that actually sent the mail, whereas the From header is on whose behalf the message was sent, since it was “from” them.

    So, for instance, if I needed to quickly send email from my wife’s account, it could have her as the Sender and me as the From. This usage is less common nowadays. A more likely scenario is that I send email from work with a sender of pcooper@checkernet.com (my work address) and a from of pete@cooperjr.name (my home address). Another good example (perhaps the best) is using some sort of “email a friend” feature on a web site, where it’s From the end-user’s email address, but the Sender is a computer program on the web server.

    This is useful for spam checking, amongst other things. My mail server could know, for instance that outside servers sending email to me won’t have a sender address ending in @cooperjr.name. That is to say, in general mail from another server isn’t legitimate if it says it’s from a user @cooperjr.name, but it could be legitimate if it says it’s from a user @cooperjr.name but its sender is a user from another domain.

  2. I just checked a handful of messages in my inbox from different ISPs, and none have a sender or x-sender header. So it looks like few people think the distinction is important enough to be worth the trouble. I do see return-path and so-called “envelope from”, but no sender.

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