While browsing about longest domain names, I found out a website which provides longest email id. You will not belive this website's domain name is 63 characters long + 4 character of (.com) domain
abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijk.com
For fun you can create yourname@abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijk... this kind of email id. I use this email id for bugging my friends.