phpmailer and the various hosting companies

I've had pretty good results with phpmailer using php 4 and now using the php 5 version. I wasn't able to set it up on Sonic.net mostly because the client wouldn't pay for the time it would have taken to get it running on Sonic using their security setting.
Now I'm have some issues with the XO Communications hosting company. They use php 4 by default so I had to load the phpmailer for that version of php. The phpmailer seems to be working but I'm receiving this warning message: "Warning: fsockopen() unable to connect to ... in /web/PHPMailer_v2.0.3/class.smtp.php on line 122"

March 23rd. Turns out that we don't have to use smtp at all. The phpmailer will deliver the email without any of the smtp, host, and password values used with smtp. On Yahoo's web hosting, they will only allow you script-generated email if the From address matches the address of the Yahoo account holder. Same goes for XO.