On 28 Nov 2018, at 1:59, Sebastian Nielsen via 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.
You should be able to use Exim's embedded Perl interpreter to do this,
after writing a suitable Perl script to call. Using the MIME::Tools
modules should make it pretty painless. See
https://www.exim.org/exim-html-current/doc/html/spec_html/ch-systemwide_message_filtering.html#SECTaddremheasys
for where to hook it in.
But, as others have said: you shouldn't.
> 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.
That's a very broken piece of software. No email client should blindly
use a Subject header as a file name without sanitizing it and no
software that saves files should crash just because its attempt to
create a file fails. I have a hard time believing that there are
actually multiple such "IMAP clients" because these basic issues are far
simpler to get right than implementing IMAP.
> 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),
Not obvious at all. Not even true on all common systems. Emoji are just
standard Unicode characters and any filesystem that can handle UTF-8 or
UTF-16 in names can use emoji. What filesystem are you using that can't
use emoji in filenames?
> and emoji in email subjects are so useless so im
> speakless...
>
> Any ideas?
Get better client software?
