For some unknown reason I suddenly stopped getting an email notification to alert me when a comment had been left on one of my blog entries regardless of the settings selected in the WP admin pages.
I tried several different options and plugins to try and fix this I even tried resorting to using a plugin to allow SMTP to send the notifications but none of them worked.
I then read this thread over on the WordPress support forums and on page 4, thanks to teknics there is a fix that worked instantly for me. Just a simple addition to my .htaccess file was all that was needed, if you alread have a .htaccess in place please be careful not to mess up anything else in the file as it could prevent your site from working.
Just adding the following line to the end of the .htaccess file was all that was needed:
<strong><span style="color: #ff0000;">php_value mail.force_extra_parameters '-f [email protected]'</span></strong>