Re: [ietf-822] Question regarding RFC 2369

Alexey Melnikov <> Sat, 21 July 2018 14:32 UTC

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From: Alexey Melnikov <>
To: Peter Occil <>
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Date: Sat, 21 Jul 2018 15:32:13 +0100
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Subject: Re: [ietf-822] Question regarding RFC 2369
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Hi Peter,
I deleted from the reply, as they are not directly
responsible for maintenance of RFC that you are quoting. I think ietf- is a better mailing list for this discussion (See
<> to subscribe) might also be of interest, as SMTP behaviour is
discussed there.
On Thu, Jul 19, 2018, at 12:24 PM, Peter Occil wrote:
> RFC 2369 sec. 2 currently says:


>    MTAs MUST NOT insert whitespace within the brackets [contained

>    in list header fields], but client applications should treat any>    whitespace, that might be inserted by poorly behaved MTAs,

>    as characters to ignore.


> To the extent the first clause applies to software generating messages
> that might contain list header fields, usually for the purpose of
> first sending them, this makes it harder for software to encode
> message header fields in a generic manner rather than having to deal
> with special cases like the list header fields, since, among other
> things, such software may seek to comply with line length limitations
> in RFC 5322 by folding long lines in accordance with that RFC.>  

> If the cited clause does apply to such software, a suggested change to
> that statement in a future revision of that RFC might be that
> whitespace "SHOULD NOT" be inserted between the brackets, but that
> software generating (as opposed to retransmitting) messages containing
> list header fields might choose to do so due to line length
> limitations in Internet messages or because of the need or desire to
> handle messages generically regardless of what header fields it has.
> (But I note that this change should not encourage MTAs to disobey SMTP
> or other transport protocols they may implement.)>  

> --Peter