A lot of people probably already know this, but I just found out. We often mix up email addresses just because they do or do not have a dot (.) in them. For example, I might have email@example.com, but people will often email me at firstname.lastname@example.org which normally would fail.
It seems that Google had the foresight to take care of this when they launched GMail. Both of the above addresses would be treated as a single one with GMail so you can put a dot anywhere in the “localpart” area and it would still work.
A small, but useful detail.