Hi,

I was thinking about this, and I would like to know if it is possible.

My idea: gpg-sign all mails to remote server which I send from my Windows PC. I mean, my email client (The Bat!, or whatever, from everywhere) connects to my account smtp (postfix), authenticates (pop-before-smtp, ehlo, ...?) and postfix gets the email. Then postfix "signs" (how?) the email using gpg (?) and queues it for either local or remote delivering.

If I understand it well (I'm a newbie w/ postfix), nobody should be able to use my smtp server to send remote emails (no open relay), but everyone could send emails using my smtp to any of the domains I host -- perfectly normal. (Note: I host email for several domains, but I want to implement this thing in only one of them). The important point is that nobody can authenticate against smtp in my account and then send emails to other servers -- I'm the only one. Correct?

That's what I plan, to take advantage of this fact and auto-gpg-sign those emails, which I send using whatever client in whatever computer (even webmail, if possible) and get them signed before delivering.

The reason: I won't need to install PGP/GPG in every computer I touch, and more important, I won't need to type my passphrase in insecure places (say a cyber, where a keylogger can be running), but my emails (and only my emails) would be digitally signed for others to trust -- if I sent them using my smtp.

I'm almost certain I would need to write a plugin or bash script or whatever to get the email signed, but does postfix allow this kind of things?

Thank you

no, well you could but it would totally defeat the point of signing your emails

Why? A lot of people have their clients automatically sign outgoing mail. Why not the server? He'll be responsible for making sure that he's the only one with the SMTP password etc etc...

It's the "etc. etc." that makes this idea weak. With straight GPG on the client, you only need to do one thing: keep your passphrase secret. The OPs proposal has a *lot* more links, of which breaking any one invalidates the whole sequence.

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