You can automate the creation of email id's but creating a http-client that is logging into you cpanel-interface and then performing the needed http-requests to create the email-ids (email accounts).
Something similar has been asked by Iain Clark (Applying .htaccess folder username/password with PHP).
If you write such an automation in PHP you can then create Email-IDs from your PHP script.
Code for similar tasks can be found here and there in the web (e.g. PHP Script To Log Into cPanel), however you should carefully check if that is dealing with your passwords appropriate and that it actually works for your version/style/theme of cpanel.
