firstname.lastname@example.org could be a valid email address as could email@example.com
Neither com.com nor mach.com.com have a valid MX record, and the A record IP for these domains does not accept an SMTP connection, so at the moment they are not valid email addresses. Unless, of course, a local mail server rewrites these addresses into something different, or someone turns on the mail server at those addresses in five minutes, in which case they most certainly are :-).
I agree completely with the general point that these are "syntactically" correct email addresses and that testing for validity in the way the OP is doing is next to useless. For a more useful approach, he should see Email::Valid. For a regular expression that checks the syntactic validity of an email, check out the Mastering Regular Expressions book (warning, IIRC the regex has approximately the length of an entire page of printed text).