On 2023-12-07, Robert Blayzor via Exim-dev <exim-dev@???> wrote:
> It seems Exim has a default limit of 998 characters per RFC on SMTP
> sending transport. If this is violated the message is rejected. I agree
> with the limit, but trying to find a way to "fix" broken senders.
>
> An optimal way may be to have an option in Exim to "wrap" lines longer
> than X. I know there is an argument on not doing this. I guess a
> transport_filter could do this, but would run into the same issue
> described below..
>
> A "workaround" for this was to pipe the message through a
> transport_filter to just truncate lines longer than 998. Again, not
> optimal, but need a fix to send these messages out without dropping them
> completely.
>
> I was able to do this with the below..
>
> remote_smtp:
> driver = smtp
> transport_filter = /usr/bin/cut -c1-998
>
>
> But it appears Exim enforces message_linelength_limit BEFORE the
> transport_filter, not after. Should the order of operation be changed to
> do this check AFTER the transport_filter?
>
> The only workaround was to do something like:
>
> remote_smtp:
> driver = smtp
> message_linelength_limit = 1M
> transport_filter = /usr/bin/cut -c1-998
yes, or
remote_smtp:
driver = smtp
message_linelength_limit = 1M
transport_filter = ${if>{$max_received_linelength}{998}{/usr/bin/cut}} -c1-998
because if the lines are all short the filter is not needed.
also possibly "fold -w998 -s" instead of "cut -c1-998"
> Not a big deal, it works. Just wondering if the linelength check should
> come after the filter and not before ...
the current check is based on the variable $max_received_linelength
adding a check that requires re-parsing the output would slow things
down.
--
Jasen.
🇺🇦 Слава Україні
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