mail() and header folding/line endings View as Markdown

PHP_EOL is \n on OS X. So the \r worries are not a
concern. PHP_EOL would be fine in this case, assuming
the OSX sendmail is fine with it.

• Davey

3. I don't have an Apple platform for testing, what will happen on
   Mac if PHP_EOL is used as the separator for $additional_headers? I
   would like to change the documentation to say "Multiple extra
   headers should be separated with the PHP_EOL constant", but I'm not
   the least bit certain this is going to work correctly on Mac. I can
   tell you that on my machines (Linux, using a mix exim and sendmail
   as MTAs), it will not see the \r as a separator, but mixing \r\n and
   \n within the same message works just fine (another case of the
   ever-prevalent SMTP mantra of "Be permissive in what you accept, and
   strict in what you send"). If PHP_EOL can't be safely used, I imagine
   we'll have to document it as 'Use "\r\n" on Win32, and "\n"
   everywhere else', which I'd really rather not do - it seems hackish.

Joey Smith wrote:

1. Maybe you could go back to Wietse and ask him to justify the
   seemingly contradictory assertions that "text is expected to be
   in native UNIX stream-LF format" [1] but "Postfix receives local
   submissions in (LF or CRLF) format" [2] and "Postfix looks at
   the first input line [to determine what format you are using]" [3]?
   It's hard to know what to tell PHP developers when we get mixed
   messages from someone like Wietse...

I think from his previous replies on the subject Postfix tolerates CRLF
formatted submissions and prefers LF, which is understandable as it is a
NIX program.

As for "other vendors", I can tell you first-hand that sendmail and
exim both handle "mixed line-endings" just fine. However, I agree that
not sending them in the first place is the ideal scenario...

Mixed line endings should never be passed to the mailer.

2. Perhaps this has changed, but last time I looked, the built-in
   SMTP client is the ONLY method available for mail() on Win32.

It is perfectly possible to use sendmail under Windows it's not really
advertised though, I've not tested it either.

3. I don't have an Apple platform for testing, what will happen on
   Mac if PHP_EOL is used as the separator for $additional_headers?

Well you are entering the realms of pre-OSX systems there, not really a
valid concern.

4. I don't write/maintain an MTA, but it seems like you're conflating
   SMTP and the "local pipe to a sendmail binary" conversation where it
   should not be. If you're sending your emails to a local pipe, I don't
   think you should be wrapping your headers in the PHP code with a LF-WSP.

I have to disagree RFC 2822 specifies the message format. While I agree
it does specify that the end of line should be CRLF and that folding is
conducted using the CRLF followed by WSP, this is not really a point of
discussion suited to PHP it is for the MTA authors. The derivation from
the RFC 2822 specification as far as I am aware is just line endings,
which ever the MTA expects should be used. I think its a fair assumption
to expect nearly all mailers to permit both CRLF and LF separated
emails, however the mail() function only permits talking LF. As stated
previously sending mixed line endings should be a total no go, as it
stands then only LF can be used by headers passed to mail().

Since PHP's mail() doesn't know if it's sending over SMTP or a local
pipe, I honestly feel that SKIP_LONG_HEADER_SEP is doing the correct
thing here - your MTA should be able to accept long headers via a
local pipe and make sure it formats them appropriately before sending
them on to their SMTP destination - PHP should only be concerned with
SKIP_LONG_HEADER_SEP in a pure SMTP situation.

It is simple to detect the method used, SMTP is used if sendmail_path is
empty and the system is Windows, otherwise sendmail is used. The
SKIP_LONG_HEADER_SEP was added for a reason back in 2003 in response to
bug #22355. [1]

Note: I just fed exim a 12000 character long subject from PHP and exim
wrapped it before sending it to the other end of the SMTP conversation.
Are you saying that Postfix does not do this?

Did you try encoding a 12000 UTF-8 string using RFC 2047 [2], this is
where the real problems emerge. Postfix will handle a really long
subject just fine, but an encoded header reaching that long gets folded
rendering it invalid. This is why it is imperative to be able to fold
the Subject and To headers in PHP, which is where it should be done.

Regards,

Chris

[1] http://bugs.php.net/bug.php?id=22355
[2] http://tools.ietf.org/html/rfc2047

--
Chris Smith

Joey Smith:

It's hard to know what to tell PHP developers when we get mixed
messages from someone like Wietse...

No, it's not so hard.
PHP developers must follow the standard:

• use "network EOL" (CRNL) when speaking SMTP;
• use "system EOL" (CRNL or NL or CR) when speaking with local MTA.
  Eventually mail() should convert "mixed line-endings" to "right
  line-endings", and "right line-endings" may be selected by the
  system administrator (a php.ini "mail_line_ending = system|network"
  switch?).

As for "other vendors", I can tell you first-hand that sendmail and
exim both handle "mixed line-endings" just fine.

Actually a "real" PHP programmer is not using mail() at all, because
nobody know where the application will be installed.

--
Tullio Andreatta

Disclaimer: "Please treat this email message in a reasonable way, or we
might get angry" ( http://www.goldmark.org/jeff/stupid-disclaimers )

2. Perhaps this has changed, but last time I looked, the built-in
   SMTP client is the ONLY method available for mail() on Win32.

I believe some people have had success in installing sendmail-like
software on Windows and using the 'linux' sendmail version.

But I could be mis-remembering...

I have no intention of commenting on the actual thrust of this \n \r\n
\r mess that has been stinking up not only php mail() but the entire
software industry for decades...

Then Chris Smith wrote:
It is simple to detect the method used, SMTP is used if sendmail_path
is empty and the system is Windows, otherwise sendmail is used.

I think you should revise this to be "if sendmail_path is empty".

Many *nix folks use SMTP as well...

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