[php-src] Issue #8086: Mail() function not working correctly in PHP 8.x

Issue: https://github.com/php/php-src/issues/8086 Comment Author: hansherlighed Thanks @cmb69 I was able to get the raw output from the mail() function into a file using your advice. You are indeed right, the raw output from PHP 8 looks like this: ``` cat -e raw_mailoutput_php8.out To: redatced@example.com^M$ Subject: This is the subject^M$ ^M$ This is the Body^M$ ``` and in PHP 7 it looks like this: ``` cat -e raw_mailoutput_php7.out To: redacted@example.com$ Subject: This is the subject$ $ This is the Body$ ``` This issue has actually been reported to PHP way back in 2002: https://bugs.php.net/bug.php?id=15841 The problem remains the same as reported in this bug. on UNIX systems, the line ending is expected to be "\n" as it is the native line ending for the system. Since PHP's mail() function on UNIX systems, is basically sending raw text output to a UNIX command(sendmail if you follow the documentation) the mail() function will not work as sendmail expects the line endings to be "\n" and NOT "\r\n". By making this new change to the mail() function so it always uses "\r\n" for the build in headers for Subject: and To:, you've actually made things worse, and made your documentation invalid. It states in the mail() documentation page: ``` Note: If messages are not received, try using a LF (\n) only. Some Unix mail transfer agents (most notably [» qmail](http://cr.yp.to/qmail.html)) replace LF by CRLF automatically (which leads to doubling CR if CRLF is used). This should be a last resort, as it does not comply with [» RFC 2822](http://www.faqs.org/rfcs/rfc2822). ``` Following this note will cause the output from PHP8 to be a mix of "\r\n" and "\n" for the headers. This will not work since the build in headers for "To:" and "Subject:" will still use "\r\n" even if you set the additional headers to use only "\n". running mail(redacted@example.com, "This is the subject", "This is the Body", "From: me@example.com\nContent-Type: text/plain");` results in: ``` cat -e raw_mailoutput_php8.out To: redacted@example.com^M$ Subject: This is the subject^M$ From: me@example.com$ Content-Type: text/plain^M$ ^M$ This is the Body^M$ ``` The essence of the problem is that a UNIX command/program expects line endings to be "\n" and not "\r\n", and since the mail() function on UNIX systems, forwards/outputs to a UNIX command rather than talking to an SMTP server directly, it causes problems. Why can't the mail() function use the same line endings as PHP_EOL, so that on windows it becomes "\r\n" and unix "\n"? That would make the function more platform independent.