For example, if your email address was firstname.lastname@example.org, you can still receive email at email@example.com or firstname.lastname@example.org. Of course if you are using Google Apps gmail.com would be your own domain name. When the email is received the "+newsletter" remains with the email address you receive.
Now why is this useful?
Well every time you enter your email address to sign up for a web based service you are open to spam as we all know in Hong Kong you cannot even trust the largest companies in Hong Kong not to sell or distribute your email address, e.g. the distrusting behavior of Octopus in 2010. So using something like email@example.com, you can achieve a couple of things:
- track where your email address was sourced from, e.g. you could prove Octopus actually shared your email address.
- you can use filters in your Gmail inbox to file the emails or just delete them.
So this is a great technique to remember to help manage your incoming email weather it is unwanted spam or subscribed services. Use the "+" and the"." more often!