[Solar-talk] Solar_Mail and newlines

[Antti Holvikari]

Guys, I think this is it:

"Note that there is a big difference between the behavior of this
function on Windows systems vs. UNIX systems. On Windows it delivers
directly to an SMTP server, while on a UNIX system it uses a local
command to hand off to the system's own MTA.

The upshot of all this is that on a Windows system your  message and
headers must use the standard line endings \r\n as prescribed by the
email specs. On a UNIX system the MTA's "sendmail" interface assumes
that recieved data will use UNIX line endings and will turn any \n to
\r\n, so you must supply only \n to mail() on a UNIX system to avoid
the MTA hypercorrecting to \r\r\n.

If you use plain old \n on a Windows system, some MTAs will get a
little upset. qmail in particular will refuse outright to accept any
message that has a lonely \n without an accompanying \r."