Re: Strict canonicalization considered harmful

From: Murray S. Kucherawy <>
Date: Tue, 9 Dec 2014 13:10:14 -0800 (PST)

On Tue, 9 Dec 2014, Alessandro Vesely wrote:
>> Certain versions of sendmail consume the leading space in a way transparent
>> to milter, so it's there in the transported version but absent in what's
>> passed to the filter. opendkim attempts to determine if the MTA it's talking
>> to has the capability not to do that, but not all versions do. The MTA flag
>> of interest is SMFIP_HDR_LEADSPC.
> I don't think it's that, as it at most inserts one space.

The actual problem is the loss of a space, but you're saying below that
lots of recent versions were tried so I'll skip that bit.

> Would you try the following for me, please?
> From: "Display phrase of 49, so total line length is 76" <>

Done, and:

Authentication System: DomainKeys Identified Mail (DKIM)
    Result: DKIM signature confirmed GOOD
    Description: Signature verified, message arrived intact
    Reporting host:
    More information:
    Sendmail milter:

> I'd be baffled if testing with a long From: field succeeds to. But I
> have no idea why a length of 76 would break anything.

Something is improperly wrapping long header fields, perhaps?

Received on Tue Dec 09 2014 - 21:10:32 PST

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