I also entered addresses I thought were fake. But there are so many registered domain names you can't make sure they are really fake.
http://voices.washingtonpost.com/securityfix/2008/03/they_to...
As others have pointed out, username@example.com is a better choice for documentation and examples.
I have since seen the light and switched over to example.com which doesn't have an MX and doesn't listen on port 25, so no harm can be done to it.
[1] https://en.wikipedia.org/wiki/Example.com
[2] http://stakeholders.ofcom.org.uk/telecoms/numbering/guidance...
I wonder if these were the general population of users seen today, since AFAIK foo/bar are not in the vocabulary of most people as metasyntactic variables; I hear "blah" more commonly used for this purpose.
uw.com was originally owned by a company called Underware. Their biggest product was a defect tracking tool called TrackRecord. They were bought by Compuware in the 90s, and in early 2000 or 2001, Compuware forgot to renew the domain and it was bought out from under them. Last I checked, two letter .com domains were pretty rare and valuable.
That was last time you checked. Now they're extremely rare and astoundingly valuable.