DKIM signatures are not a problem, as incoming mail are validated
Before applying any rules, and outgoing mail is signed last, after all
rules have been applied.
The server never passes already-signed email to a third-party server,
it Always act as a source-signer or destination-verifier, ergo either
its the final destination of email and DKIM is being verified Before
rules are applied, or its the first MTA after user's SMTP client, and
thus it will apply rules and then sign the email.
Den ons 28 nov. 2018 kl 11:09 skrev Mike Brudenell via Exim-users
<exim-users@???>:
>
> Hi, Sebastian -
>
> What you suggest doesn't sound to be a good idea to me, unless you're
> planning to do it *only* at the point of final delivery into the
> recipient's mailbox. (You saying you'll make the change then "send the
> message along" suggests you're not thinking of doing this though, but
> applying it to all messages as they pass through.)
>
> I say this because of the message has been digitally signed using DKIM
> altering the Subject line will invalidate the signature and possibly cause
> problems at any downstream mail servers the message is transmitted to:
> possibly causing the message to be marked as spam or rejected.
>
> If the problem lies in certain IMAP clients your users use wouldn't it be
> better to report the bug in them and get them fixed? It sounds like they're
> broken!
>
> Cheers,
> Mike B-)
>
> On Wed, 28 Nov 2018 at 07:04, Sebastian Nielsen via Exim-users <
> exim-users@???> wrote:
>
> > How can I reliably cut subjects that are too long, without breaking
> > for example quoted-printable encodings and such?
> >
> > Ergo, if the subject line exceeds X characters (where X characters are
> > a limit I as system administrator decides) it should just truncate the
> > decoded subject line, reencode it, and then send the mail along.
> >
> > The reason I want to do it, is because some IMAP clients do crash when
> > it tries to export/backup email with too long subject lines as it
> > tries to write the subject as a filename, and the operating system
> > returns a error code the IMAP client don't understand = crash.
> >
> > Also I want in the same way, filter away all and any emojii (for
> > example the truck in Ebay's "Order is now being delivered" emails)
> > from subject lines because emojii also causes these IMAP clients im
> > talking about to crash (because obviously emojii can't be used as
> > filenames), and emoji in email subjects are so useless so im
> > speakless...
> >
> > Any ideas?
> >
> > --
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> >
>
>
> --
> Systems Administrator & Change Manager
> IT Services, University of York, Heslington, York YO10 5DD, UK
> Tel: +44-(0)1904-323811
>
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