dovecot - Jun 2014 - Subject tag is gone

I've actually been thinking about it almost since the beginning. It's
just been annoying waste of space on my screen. And more importantly nowadays
it's also breaking DKIM/DMARC signatures. So if somebody still uses
Subject-based filtering it's about time to switch to List-ID header based
filtering now.

Another thing I'm wondering about is if I should allow text/html parts,
because removing them will also break the DKIM signatures. Or mainly I'd
like to allow only multipart/alternative with text/plain + text/html, but I
don't think I can configure Mailman to support that.

op 09-06-14 22:27, Timo Sirainen schreef:
> I've actually been thinking about it almost since the beginning.
It's just been annoying waste of space on my screen. And more importantly
nowadays it's also breaking DKIM/DMARC signatures. So if somebody still uses
Subject-based filtering it's about time to switch to List-ID header based
filtering now.
>
> Another thing I'm wondering about is if I should allow text/html parts,
because removing them will also break the DKIM signatures. Or mainly I'd
like to allow only multipart/alternative with text/plain + text/html, but I
don't think I can configure Mailman to support that.
>
Hi,

Just wanted to ask what happened to "[Dovecot]" when I saw this mail. 
Could you tell me how to find the List_ID ? I looked at the raw mail, 
but I didn't find it :

some removed stuff and anonymized...
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From: Timo Sirainen <tss<at>iki.fi>
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Subject: Subject tag [Dovecot] is gone
Message-Id: <A864F144-2962-4963-BEE6-5A6CBB738BDA at iki.fi>
Date: Mon, 9 Jun 2014 23:27:41 +0300
To: Dovecot Mailing List <dovecot at dovecot.org>
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I've actually been thinking about it almost since the beginning. It's
just been annoying waste of space on my screen. And more importantly nowadays
it's also breaking DKIM/DMARC signatures. So if somebody still uses
Subject-based filtering it's about time to switch to List-ID header based
filtering now.

Another thing I'm wondering about is if I should allow text/html parts,
because removing them will also break the DKIM signatures. Or mainly I'd
like to allow only multipart/alternative with text/plain + text/html, but I
don't think I can configure Mailman to support that.

On 06/09/2014 01:27 PM, Timo Sirainen wrote:
> 
> Another thing I'm wondering about is if I should allow text/html parts,
because removing them will also break the DKIM signatures. Or mainly I'd
like to allow only multipart/alternative with text/plain + text/html, but I
don't think I can configure Mailman to support that.

Yes you can, well sort of - see below, but note that in addition to
content filtering, the addition of msg_footer will probably break DKIM
signatures.

If you put the following in pass_mime_types

multipart/alternative
text/plain
text/html

and set both collapse_alternatives and convert_html_to_plaintext to No,
multipart messages which are not multipart/mixed (e.g., multipart/mixed,
multipart/related and multipart/signed) will be handled according to
filter_action. Messages which are multipart/alternative with only
text/plain and text/html alternatives will be passed unchanged by
content filtering as will single part messages of type text/plain or
text/html.

Potential problems with this are:
1) you may not want single part text/html on the list.
2) some people sign their posts.

Because of 2), you need to add multipart/signed and
application/pgp-signature to pass_mime_types, but that complicates the
content filtering scenario because now a message with a structure like

multipart/signed
    text/plain
    application/pgp-signature
    image/jpeg

will be accepted by the list with the image/jpeg part removed rather
than handled according to filter_action.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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