As you might know, theres lots of MUA's out of there that does not produce completely RFC compliant email. Not even Windows Live Mail, Windows Mail (the builtin Email client of Windows 8/8.1) and Outlook produce fully compliant email, and those mail clients are in most wide use today. Many MUA's even lie straight out about how the email is formatted, yet still most MUA's can display the email correctly. Lotes Notes are even worser, they produce HTML email that they send as text/plain, causing HTML code to be displayed in most MUA's.
Sometimes you even need to put specific "work around" rules for specific MUA's in MTA's to fix certain RFC-ignorant MUA's at MTA level. Thats why most protocols needs "autodetection" and fix eventual formatting errors. For example IE detect when a web server sends a resource with a incorrect Content-Type and tries to "auto-detect" the content-type to make the document display correctly.
I like when things are really transparent, where things are adjusted so you can basically use whatever client software you wish, and still it works. Thats why I like when people put Email signing, Email verification and such duties at the MTA level, so the MUA does not need to care or support whatever its about.
Best regards, Sebastian Nielsen-----Ursprungligt meddelande----- From: Wietse Venema
Sent: Wednesday, February 25, 2015 2:40 PM To: Postfix users Subject: Re: Signing-milter - are postfix tampering with messages? Sebastian Nielsen:
How can this be accomplished at MTA end? Any good "Make message RFC" milterthat canonalizes the message according to RFC 5321, RFC 5322, RFC 2045 or something?
I am not interested in software that converts random garbage into RFC-compliant email. This problem needs to be fixed at its source, not by piling on a layer of band-aids. The way to make your signatures robust is to never break the rules of the Internet.Wietse
smime.p7s
Description: S/MIME cryptographic signature
