Solution 1 (The easiest):
Please check that you have turned on Sendmail in your cPanel under | cPanel > Settings > General > Scroll down to Sendmail | and turn it on (if it was off).
If Sendmail is already turned on, jump to solution 2.
Solution 2:
You may have reached the limits, to check them, go to the Statistics page (cPanel > Settings > Statistics)
If you have reached 100%, you will have to wait for the next day for them to reset.
Haven’t reached 100%?
Let’s proceed to solution 3.
Solution 3:
If none of the above solutions worked, you have most likely a coding error, here’s a working code for the mail() function:
<?php
$to = "THE ADDRESS YOU WANT TO SEND THE EMAIL TO";
$subject = "YOUR SUBJECT HERE";
$body = "YOUR BODY GOES HERE";
$headers = "MIME-Version: 1.0
Content-Type: text/html; charset=UTF-8";
mail ($to, $subject, $body, $headers);
?>
That should most likely solve your errors.
In conclusion…
If that didn’t work, feel free to ask us for help, we are here for that ;)!