Broken linebreaks in auto-generated mails on hosts using qmail #644
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th-h
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Oct 13, 2019
s9y will encode the body of its auto-generated mails as quoted-printable when imap_8bit() is available. imap_8bit() will use "\r\n" as linebreaks as mandated for SMTP transfer. The result will be transmitted via PHP's mail() function, using direct SMTP on Windows and piping it to a MTA on Unix. Most MTAs will cope just fine with those linebreaks, while qmail will not; it will replace all "\n" linebreaks with "\r\n", so we get "\r\r\n" in our case. We can't "fix" qmail (as its maintainer, if there even is one, does not consider this behaviour wrong), but we can replace the line endings we get from imap_8bit(). The fix does work with qmail and Exim and should work with sendmail and Postfix and other MTAs, too. It may break sending mail on Windows (i.e. lose all linebreaks), but I think that's acceptable, as we'll have more qmail installation than Windows servers out there. A workaround could be to set serendipity['forceBase64']=true in serendipity_config_local.inc.php, but I'd prefer this fix. Fixes s9y#644. Signed-off-by: Thomas Hochstein <thh@inter.net>
th-h
added a commit
to th-h/Serendipity
that referenced
this issue
Oct 13, 2019
s9y will encode the body of its auto-generated mails as quoted-printable when imap_8bit() is available. imap_8bit() will use "\r\n" as linebreaks as mandated for SMTP transfer. The result will be transmitted via PHP's mail() function, using direct SMTP on Windows and piping it to a MTA on Unix. Most MTAs will cope just fine with those linebreaks, while qmail will not; it will replace all "\n" linebreaks with "\r\n", so we get "\r\r\n" in our case. We can't "fix" qmail (as its maintainer, if there even is one, does not consider this behaviour wrong), but we can replace the line endings we get from imap_8bit(). The fix does work with qmail and Exim and should work with sendmail and Postfix and other MTAs, too. It may break sending mail on Windows (i.e. lose all linebreaks), but I think that's acceptable, as we'll have more qmail installation than Windows servers out there. A workaround could be to set serendipity['forceBase64']=true in serendipity_config_local.inc.php, but I'd prefer this fix. Fixes s9y#644. Backported from master branch. Signed-off-by: Thomas Hochstein <thh@inter.net>
robelix
pushed a commit
to robelix/Serendipity
that referenced
this issue
Mar 9, 2020
s9y will encode the body of its auto-generated mails as quoted-printable when imap_8bit() is available. imap_8bit() will use "\r\n" as linebreaks as mandated for SMTP transfer. The result will be transmitted via PHP's mail() function, using direct SMTP on Windows and piping it to a MTA on Unix. Most MTAs will cope just fine with those linebreaks, while qmail will not; it will replace all "\n" linebreaks with "\r\n", so we get "\r\r\n" in our case. We can't "fix" qmail (as its maintainer, if there even is one, does not consider this behaviour wrong), but we can replace the line endings we get from imap_8bit(). The fix does work with qmail and Exim and should work with sendmail and Postfix and other MTAs, too. It may break sending mail on Windows (i.e. lose all linebreaks), but I think that's acceptable, as we'll have more qmail installation than Windows servers out there. A workaround could be to set serendipity['forceBase64']=true in serendipity_config_local.inc.php, but I'd prefer this fix. Fixes s9y#644. Signed-off-by: Thomas Hochstein <thh@inter.net>
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What s9y does
Serendipity will convert the body of auto-generated mails to quoted-printable if
imap_8bit()is available, and to base64 otherwise. Quoted-printable will trim all lines to less then 76 characters and add "soft" linebreaks; "real" linebreaks ("\n") will be encoded, too (as "=A0"). Decoding will go the other way around. The mail will be send using PHP'smail()function.The way it should go
So, the text
will be encoded to
and decoded right back to the original text.
What goes wrong
But sometimes, those messages will get mangled, due to extra linebreaks. The encoded message will now look like this:
The decodes message will now look mangled like this:
The cause of this problem
... seems to be qmail (again). I couldn't reproduce the problem, as all my hosts run Exim as MTA; but Uberspace does not, the use qmail. Using a little test script, I can confirm that messages delivered using
mail()on a host running Exim (and sendmail, and probably Postfix, too) will arrive just fine, but on a host running qmail (especially on corvus) will get mangled.Old messages from more than 15 years ago seem to pin the problem to qmail's handling of linebreaks in incoming mail.
imap_8bit()will use\r\nas linebreaks as mandated in RFC 822 (and its descendants). Most MTAs can handle that, but qmail seems to insist on getting an ordinary UNIX text file as input and converting all\nlinebreaks to the\r\nneeded for SMTP transmission, so we get\r\r\n. That's one\rtoo much, leading to our problems. It's even documented on the PHPmail()page ...The text was updated successfully, but these errors were encountered: