On Sun, Jun 29, 2014 at 8:20 AM, Wietse Venema <wie...@porcupine.org> wrote:
> Mauricio Tavares:
>> [<-] 220 mail.domain.com Test Mail Server
>> [->] HELO raub.internal.domain.com
>> [<-] 250 mail.domain.com
>> [->] MAIL FROM:<r...@desktop.internal.domain.com>
>
> You send HELO. That means you can only send 7-bit ASCII email.
> Please read RFC 5321 for the 7-bit requirement of SMTP.
>
> In order to send 8BIT mail over SMTP, the client must announce that
> it supports ESMTP, the server must announce that it supports 8BITMIME,
> and the client must issue the 8BITMIME parameter in the MAIL FROM
> command.
>
> Please read RFC 1869 for how to negotiate ESMTP.
> Please read RFC 1652 for how to negotiate 8BITMIME.
>
So, based on those two RFCs, the transaction should look something like:
raub@desktop:/tmp$ nc -t mail.domain.com 25
220 mail.domain.com Test Mail Server
EHLO desktop.domain.com
250-mail.domain.com
250-PIPELINING
250-SIZE
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
MAIL FROM:<r...@domain.com> BODY=8BITMIME
250 2.1.0 Ok
RCPT TO:<r...@domain.com>
250 2.1.5 Ok
DATA
354 End data with <CR><LF>.<CR><LF>
From: "Mauricio Tavares" <r...@domain.com>
Subject: 8bit test - manual6
Date: Mon, 30 Jun 2014 11:10:05 -0400
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Olivenöl
.
250 2.0.0 Ok: queued as 2BA1F80041
QUIT
221 2.0.0 Bye
raub@desktop:/tmp$
or am I missing something?
>> > As required by the MIME RFCs, an MTA must either bounce mail or
>> > convert it to quoted-printable when it needs to deliver 8BITMIME
>> > mail to an SMTP server that does not announce 8BITMIME support.
>> >
>> > DKIM signatures of 8BITMIME mail may break unless all SMTP servers
>> > in the path implement and announce 8BITMIME support. Otherwise, it
>> > is better to down-convert to quoted-printable before DKIM signing.
>> >
>> Can I down-convert the email in postfix before DKIM signing? I
>> believe some email clients using this server are sending 8BITMIME
>> emails without a properly created MAIL FROM command line. Since I
>> cannot do the right thing and correct that at the MUA side, I would
>> like to do the next best thing.
>
> You can force downconversion with a null content filter and by
> suppressing or ignoring the 8BITMIME server announcement.
>
> Untested example:
>
> /etc/postfix/master.cf:
> smtp .. .. .. .. .. .. .. smtpd
> -o content_filter=dummy:127.0.0.1:12345
>
> dummy .. .. .. .. .. .. .. smtp
> -o smtp_discard_ehlo_keywords=8bitmime,silent-discard
>
> 127.0.0.1:12345 .. .. .. .. .. .. .. smtpd
> -o smtpd_authorized_xforward_hosts=127.0.0.1
> -o smtpd_client_restrictions=
> -o smtpd_helo_restrictions=
> -o smtpd_sender_restrictions=
> -o smtpd_relay_restrictions=
> -o smtpd_recipient_restrictions=permit_mynetworks,reject
>
> Once mail is received with the 127.0.0.1:12345 SMTP server, it will
> have been down-converted, provided that it was formatted properly,
> and that the proper ESMTP commands were used.
>
> Wietse
