It’s important to have good quality passwords. Including a combination of upper and lower case letters, numbers, and punctuation marks in your password will make for a tougher password than a simple word (w1Nt.e!r is a much harder password to break than winter) . However, remembering such passwords can be difficult.
To achieve this, one approach is to use email addresses as passwords. Many email addresses contain underscores and numbers and all of them contain the @ sign and periods. If you use email addresses as passwords, your passwords will automatically be more secure.
Now obviously you should not use a easy to guess email address as your password. You don’t even have to use a real email address: me@myT0ughPassw0rd.heck.ya.times.1000 will also work well. The challenge is to have a password you can recall with one that is harder to break. This approach helps with that.
Smart People I Know 
Using an e-mail address aside from making things more secure would probably make things easier to type for some people.
Reason being that an e-mail address is a commonly typed set of characters. This is true even with our address books and look ups and such as we sometimes still need to type new ones in. Therefore the more you type it or something similar the faster you get, and the faster you get at typing something, the harder it is for someone to look over your shoulder and figure out your password.
Good point, Archie! I hadn’t thought of that, but it’s likely true.