Total speculation, but maybe they're trying to be clever and accept things like ...

		mikeash on July 27, 2015 \| parent \| context \| favorite \| on: Steam hit by major security breach Total speculation, but maybe they're trying to be clever and accept things like "John Doe <john@doe.com>" as being equivalent to "john@doe.com" and end up using a full e-mail parsing library for the matching which is more capable than they realize?