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Article: 1064
From: Anthony Howe
Date: 2010-09-08 11:21:07 -0400
Subject: Re: fixcrio in milter

On 08/09/2010 16:51, Geoff Adams whispered from the shadows...:
> On 8 Sep 2010, at 10:24 AM, Anthony Howe wrote:
> 
>> I am unaware of any bare LF issues in the current versions of my milters.
> 
> I read the Hans's note as a request for a feature (well, a request to
> know if your milters have the feature) to fix up line endings in
> messages that come in incorrectly in the first place. Honestly, I can't

That's not the milter's job, that is for the MUA or MSA to do at the
point of insertion into the mail system; the sender is responsible for
making sure the message conforms. The reason for this is simple when you
consider DKIM/PGP signed messages; body modifications would break
digital signatures. Also the fact that messages that fail to handle
generate properly formatted messages might be considered a spam sign.

Then there is the issue that some unix MTAs will receive the message via
SMTP with CRLF ending, save it to a queue / temp. file with LF endings
and it is that file contents that is passed to the milter. I've not
checked if sendmail or postfix do this recently.

> say I've seen a problem with that in real mail, but perhaps qmail is

qmail is rubbish IMO. The two MTAs I've had the most trouble with in the
past have been qmail and Exchange. (infer rant here)

> more strict in this regard. I'd expect that that's a feature, though,
> and that any incoming mail that has incorrect line endings would likely
> be spam, and best rejected.

Yes. Still this is an issue with the MTA, not the milter which is just a
plugin for the MTA. So if there is a LF vs CRLF issue, that should be
directed at sendmail / postfix.

> Judging by the link Hans included, it seems like sending LFs instead of
> CRLFs, which is strictly forbidden by the relevant RFCs, will cause
> other problems for the sender, as well. Further, the noted sending MTA
> versions that exhibit this problem are quite old. Actually, pretty much
> ancient. It doesn't seem like this should be a problem today.

It shouldn't be and I would have heard of these issues years ago when I
first wrote the milters. In BarricadeMX, which handles the SMTP
connection directly, I've gone to great lengths to handle LF vs CRLF
issues as best as I can. In the milters however they are feed the data
from the MTA, so it is upto the MTA to ensure that data corresponds to
the original received. And as a rule, no SnertSoft milter modifies body
content, only headers and that case libmilter/sendmail/postfix handle
newline conversion/additions.

> Hans, why don't you get the senders to correct the actual problem, if I
> understand correctly, and there are sending MTAs violating the SMTP spec?

This is most likely the case. A very old MTA.

Still Hans' bug report/enhancement is too vague. It mentions four
milters and no version numbers.

There was an issue sometime ago with milter-spamc / spamd and CRLF
handling between them, but that was like 18 months ago or more. Still
that doesn't sound like his issue.

-- 
Anthony C Howe            Skype: SirWumpus                  SnertSoft
+33 6 11 89 73 78       Twitter: SirWumpus      BarricadeMX & Milters
http://snert.com/      http://nanozen.info/     http://snertsoft.com/

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