Try deleting the account definition in X-Notifier, (maybe delete the script and reload it), then restart the browser and redefine the account... because it works for other users. I have three mail.com related accounts and it works fine as soon as I installed the update.
Update
And if you would look, you'll see there's a new updated script for mail.com, 08-04-2015
http://xnotifier.tobwithu.com/scripts.php
XN-scripts
And you can get X-notified for script updates by adding the XN-scripts account to your XN accounts (in XN Options - Accounts tab).
Mail.com
Lastest update still not working.
Troubleshoot
Try deleting the account definition in X-Notifier, (maybe delete the script and reload it), then restart the browser and redefine the account... because it works for other users. I have three mail.com related accounts and it works fine as soon as I installed the update.
Mail.com
Thanks Troubleshoot -- your suggestion of deleting account, reloading script and restarting Firefox solved my issues.
RpD
Troubleshoot says: you're welcome