Yep. If you have a Gmail or GoogleMail email address, you can use either domain name suffix in your email address. It would appear that at one time, Googlemail.com was a U.K. only domain for Gmail and then Google gave users the option to switch it to gmail.com.
Did you also know that Gmail (aka GoogleMail) ignores all periods in the email address prefix for Gmail/GoogleMail email addresses?
Yep. This means that "firstname.lastname@example.org", "email@example.com", and "firstname.lastname@example.org" are all the same addresses.
Every once in a while I get an email intended for another Scott Paterson, whom I believe lives somewhere in the U.K. It would appear that the other Scott Paterson is using the "scottpaterson AT googlemail.com" email address.
Unfortunately for that Scott, he'll never get any email intended for him because I happen to have the "scott.paterson AT gmail.com" email address and anything sent to him shows up in my inbox.
This makes me wonder if the other Scott ever tries to read his email, or if he just uses it to prevent receiving spam, because I can't see how he could ever log into Gmail to read the email. From what I read in the first link I posted above, he would have had to click an option to make the change from googlemail.com to gmail.com. If that’s the case, I’m kinda surprised that it was allowed since I’ve had the “scott.paterson AT gmail.com” for a long time.