著者: Phil Pennock 日付: To: exim-users 題目: Re: [Exim] does exim not follow the RFC 1652 ?
Typing away merrily, Dave C. produced the immortal words: > The exim config file gives the administrator of a system running exim
> the capability to decide wether they wish exim to offer that feature or
> not. Some sites may wish to not permit this feature.
By my understanding of the documentation,
Off => RFC compatible
On => Broken
RFC 1652 (SMTP Service Extension for 8bit-MIMEtransport):
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Once a server SMTP supporting the 8bit-MIMEtransport service
extension accepts a content body containing octets with the high-
order (8th) bit set, the server SMTP must deliver or relay the
content in such a way as to preserve all bits in each octet.
If a server SMTP does not support the 8-bit MIME transport extension
(either by not responding with code 250 to the EHLO command, or by
not including the EHLO keyword value 8BITMIME in its response), then
the client SMTP must not, under any circumstances, attempt to
transfer a content which contains characters outside the US-ASCII
octet range (hex 00-7F).
A client SMTP has two options in this case: first, it may implement a
gateway transformation to convert the message into valid 7bit MIME,
or second, or may treat this as a permanent error and handle it in
the usual manner for delivery failures. [...]
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Exim documentation (3.10, latest docs in HTML):
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Option: accept_8bitmime
Type: boolean
Default: false
This option causes Exim to send 8BITMIME in its response to an SMTP EHLO
command, and to accept the BODY= parameter on MAIL commands. However,
though Exim is 8-bit clean, it is not a protocol converter, and it takes
no steps to do anything special with messages received by this route.
Consequently, this option is turned off by default.
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So whilst Exim might receive fine, and handle fine, it won't forward on
to non-8-bit-clean systems in compliance with the RFC.
AIUI. And hence I keep the option off.
--
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