One of the cool features that was added to GMail was the ability to add a +
For instance, if your gmail id is myaccount@gmail.com, someone could send you emails by using myaccount+friends@gmail.com.
So, you could give your email id as myaccount+friends@gmail.com to all your friends, you could subscribe to bogleheads as myaccount+bogleheads@gmail.com, subscribe to kohls weekly promotions as myaccount+kohls@gmail.com etc.,
Advantages? You could easily search emails by the keyword(+friends,+bogleheads) and you could also find out who is selling out your emails to spammers!
You could also add any number of periods(.) to the part preceding the @ sign in your email id, so, my.account@gmail.com, m.y.a.c.c.o.u.n.t@gmail.com are all valid email ids of myaccount@gmail.com
Have fun.
Sanjay.
