The PHPMailer class included with simpleContact defaults to SMTP port 25. You may want to use another port (e.g. to use authenticated SMTP through the "submission port" 587), so here is a simple hack that shows you how to change the port:
simpleContact Lite 1.0
Version 1.0 does not include PHPMailer. Download the latest simpleContact Lite to use this hack.
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simpleContact Lite 1.1, 1.2
Open sc_admin/include/common/functions.php
Find the sendMessage() function at the bottom of the script. Find the line that says...
$mail->Host = $smtp_server;
... add this line after it (where x is the desired port number) ...
$mail->Port = x;
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simpleContact Pro 2.0
Open sc_admin/include/common.php
Find the sendMessage() function at the bottom of the script. Find the line that says...
$mail->Host = $smtp_host;
... add this line after it (where x is the desired port number) ...
$mail->Port = x;