dovecot - Apr 2008 - Problem with Dovecot Delivery Agent, Extra "From" lines and mbox

When an mbox email contains a line that looks like a "Mail" header
it should be quoted (per RFC 4155). Sendmail's delivery agent does
this, as does Procmail delivery agent.  Dovecot deliver does not
do this.

Example line, with ">" quote:
>From hokan at hokan.org Thu Mar  8 17:28:01 2008
When reading email (IMAP) that contains such an unquoted line, the
email abruptly ends before the "Mail" line.  There may (or may not)
appear another email (visible to the client) that contains the rest 
of the email.

-- 
Hokan                           MEnet, a wholly owned subsidiary of Enet
System Administrator                Department of Mechanical Engineering
hokan at me.umn.edu                                 Institute of Technology
612.626.9800                                     University of Minnesota

Perhaps a demonstration will make the problem more clear.

If you are using Dovecot Deliver v 1.03 or 1.13 and most any IMAP
server (I am using Dovecot IMAP) then I expect you will not see
the rest of this email.  Look at your INBOX directly on the server
for more:
>From hokan at hokan.org Thu Mar  8 17:28:01 2008
On Wed, Apr 09, 2008 at 04:03:58PM -0500, Hokan wrote:
> When an mbox email contains a line that looks like a "Mail"
header
> it should be quoted (per RFC 4155). Sendmail's delivery agent does
> this, as does Procmail delivery agent.  Dovecot deliver does not
> do this.
> 
> Example line, with ">" quote:
> >From hokan at hokan.org Thu Mar  8 17:28:01 2008
> 
> When reading email (IMAP) that contains such an unquoted line, the
> email abruptly ends before the "Mail" line.  There may (or may
not)
> appear another email (visible to the client) that contains the rest 
> of the email.
> 
 
-- 
Hokan                           MEnet, a wholly owned subsidiary of Enet
System Administrator                Department of Mechanical Engineering
hokan at me.umn.edu                                 Institute of Technology
612.626.9800                                     University of Minnesota

On Wed, 2008-04-09 at 16:03 -0500, Hokan wrote:
> When an mbox email contains a line that looks like a "Mail"
header
> it should be quoted (per RFC 4155). Sendmail's delivery agent does
> this, as does Procmail delivery agent.  Dovecot deliver does not
> do this.
> 
> Example line, with ">" quote:
> >From hokan at hokan.org Thu Mar  8 17:28:01 2008
> 
> When reading email (IMAP) that contains such an unquoted line, the
> email abruptly ends before the "Mail" line.  There may (or may
not)
> appear another email (visible to the client) that contains the rest 
> of the email.
Dovecot is supposed to use Content-Length: header to skip over the mail
body so it wouldn't require From lines to be quoted. This used to work
with v0.99, but it got broken at some point.

I've also thought about quoting From line, and maybe I'll do that if I
can't get Content-Length: to work properly. An annoying problem with the
quoting is that it changes the mail content and breaks things like PGP
signatures.

Anyway this is in my "would be a nice fix for v1.1.0, but doesn't block
a release" TODO category.
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On Fri, Apr 25, 2008 at 03:03:14AM +0300, Timo Sirainen
wrote:
> On Wed, 2008-04-09 at 16:03 -0500, Hokan wrote:
> > When an mbox email contains a line that looks like a "Mail"
header
> > it should be quoted (per RFC 4155). Sendmail's delivery agent does
> > this, as does Procmail delivery agent.  Dovecot deliver does not
> > do this.
> > 
> > Example line, with ">" quote:
> > >From hokan at hokan.org Thu Mar  8 17:28:01 2008
> > 
> > When reading email (IMAP) that contains such an unquoted line, the
> > email abruptly ends before the "Mail" line.  There may (or
may not)
> > appear another email (visible to the client) that contains the rest 
> > of the email.
> 
> Dovecot is supposed to use Content-Length: header to skip over the mail
> body so it wouldn't require From lines to be quoted. This used to work
> with v0.99, but it got broken at some point.
> 
> I've also thought about quoting From line, and maybe I'll do that
if I
> can't get Content-Length: to work properly. An annoying problem with
the
> quoting is that it changes the mail content and breaks things like PGP
> signatures.
> 
> Anyway this is in my "would be a nice fix for v1.1.0, but doesn't
block
> a release" TODO category.
Thanks for the reply!

This is a big problem when it happens; very confusing for the end user.
But it seems to be a rare occurance.