Text Formatting

I have a large list composed of three columns, First name, Last name, and Email address. For the most part names and emails match up perfectly but there are an unknown number of names that do not match their email address. Here’s the hard part, email addresses are in different formats for example:

some are firstname.lastname@somewhere.com but others can be lastname.firstname@somewhere.com or some email addresses are first name initial then full last name with no dot separator @somewhere.com and even turned around like Last name initial then first name. For the most part this is the only four ways the emails are configured but all email addresses have some variation of last and first name in them.

How can I find the number of email addresses that do not match their names?

I warned you that it was hard.