Yes it is. It's a feature by gmail.

You can put as many "." as you want in your email address, and you'll receive email from every variation. [email protected] and [email protected], etc. Gmail does that if you want to use that to help filter your email.

The other feature it has to help you filter your email is "+". So [email protected], [email protected], [email protected], etc. will all go to you as well. Again, using whatever keywords/variables you deem important to help you filter, flag, and sort your own email. (Like automatically flag +donation as read and archive it, or autodelete everything with +junk)