ESMTP CHUNKING

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ESMTP CHUNKING

J Doe
Hi,

I have been reading about the ESMTP CHUNKING extension (RFC 3030), after noticing that both Hotmail and Gmail advertise it on EHLO.  

I checked the Postfix man pages (man 5 postconf), as well as the Postfix documentation at postfix.org [1] and can’t see any documentation related to it.

Some Googling of the mail archives showed posts from 2014, while another Google showed a reference [2] to Postfix from 2017:

    “IMSVA (SMTP server) uses Postfix as its MTA, which doesn’t support CHUNKING”

Given Postfix’s excellent security track record, was this extension not implemented due to security concerns or is it obsolete (I checked the RFC and didn’t see a notice of being obsolete), and Hotmail and Gmail advertise it for legacy support ?

Genuinely curious and not an implementation request or criticism.

Thanks,

- J

Sources:
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Re: ESMTP CHUNKING

Viktor Dukhovni


> On Mar 1, 2018, at 3:42 PM, J Doe <[hidden email]> wrote:
>
> I have been reading about the ESMTP CHUNKING extension (RFC 3030), after noticing that both Hotmail and Gmail advertise it on EHLO.  
>
> I checked the Postfix man pages (man 5 postconf), as well as the Postfix documentation at postfix.org [1] and can’t see any documentation related to it.

There is little need for CHUNKING.  It is unnecessary complexity for rather modest
data compression (avoiding base64 encoding when the message originates from an MUA
that supports BINARYMIME and CHUNKING and the same is true of every MTA along the
path).

Exim implemented chunking and had a long string of bugs until they ironed out all
the issues.  In Postfix my sense is that it is not a worthwhile feature.

--
        Viktor.

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Re: ESMTP CHUNKING

Wietse Venema
In reply to this post by J Doe
J Doe:
> Hi,
>
> I have been reading about the ESMTP CHUNKING extension (RFC 3030),
> after noticing that both Hotmail and Gmail advertise it on EHLO.
>
> I checked the Postfix man pages (man 5 postconf), as well as the
> Postfix documentation at postfix.org [1] and can?t see any
> documentation related to it.

Unfortunately, Postfix documentation can only describe what is
supported. Describing all the things that aren't supported would
not be practical.

> Some Googling of the mail archives showed posts from 2014, while
> another Google showed a reference [2] to Postfix from 2017:
>
>     ?IMSVA (SMTP server) uses Postfix as its MTA, which doesn?t
>     support CHUNKING?
>
> Given Postfix?s excellent security track record, was this extension
> not implemented due to security concerns or is it obsolete (I
> checked the RFC and didn?t see a notice of being obsolete), and
> Hotmail and Gmail advertise it for legacy support ?

Every (software) feature has a non-zero cost, and resources are
finite.

        Wietser