Check for errors within your forum error log
Common errors you will see within your error log are:
- Could not connect to SMTP host
- 2: fsockopen() has been disabled for security reasons
This error is pretty self explanatory in that your error log is telling you that the SMTP information you have provided is not correct, i.e cannot connect to send your mail. Check the information again and contact your host to make sure the information you are entering is correct.
The second error message listed above indicates your webhost has disabled the PHP default setting for sending mail from your SMF installation. You will need to contact your host and ask them to enable this for you.
Is my server blacklisted?
Because of the growth of spam these days it is quite possible that your emails are being detected as spam!
The following links will help you find information regarding any potential blacklist your server may be listed on.
http://www.us.sorbs.net/
http://openrbl.org/
Using GMAIL SMTP?
If you use Gmail for SMF's SMTP - meaning to send emails from SMF. Gmail will not work in most cases. Gmail will only accept SSL encrypted emails, which most servers do not support.
Server configured correctly for sending mail?
To check if your server is configured correctly for sending mail then use this test script below. Just replace the YOUR-EMAIL-HERE with your own email address
to check if the mail function works, if it fails, try using SMTP. IMPORTANT: Remember to remove this test script immediately.
Save as testmail.php and upload to your server.
If you do not receive an email from your server then contact your host and explain you currently cannot send mail from your forum. During this time you will have to use the SMTP settings for sending mail rather than the (php) default value.
Code: [Select]
<?php
$mail = mail("YOUR-EMAIL-HERE", "wahahahahahaahahahahaa","I like spamming your inbox!!!", "From: Myself<your_email@here.com");
if(!$mail){
echo '<font color="red">mail is not send!</font>';
} else {
echo '<font color="#00FF00">mail is send :-)</font>';
}
?>Again, be sure to delete the test script when finished, or spam email can be sent to the email address used in the script.

Why are members not getting emails sent from the forum?
Some hosts disable the default PHP mailer in place of their own. In this case, you need to set up your forum to use SMTP. You can do so through Server Settings -> Feature Configuration