You should not have to add a port number to get mail to work.
On thins you could check if you can actually send email on your server. here is a script that you could test on your page:
$to = "firstname.lastname@example.org";
$subject = "Test mail";
$message = "Hello! This is a simple email message.";
$from = "email@example.com";
$headers = "From: $from";
echo "Mail Sent.";
echo "Mail was not sent";
and if you get the "Mail Sent" message, then you have mail running but if you get "Mail was not sent" then you don't mail server and you need to contact your server provider.
The script is the simplest form of sending emails.