There’s a great trait of most major email providers sometimes called plus addressing.

It gives you access to unlimited email addresses based off your one single email account. If you add a “+” sign in your email name, followed by anything, it will still get delivered to your inbox. So:

Lots of power-users use this feature to help automatically filter email into folders/labels. Some give out a unique email to every site to help figure out which services are selling their address to spammers.

This feature is probably supported by your mail provider. At least including GMail, Yahoo, Microsoft, Apple, and FastMail. (And if that doesn’t cover you, you probably have bigger problems, like you are running your own inbound mail server, yikes!)

Support Emails With +’s

Pretty please, if you have a signup form in your application that takes email addresses, test to be sure it accepts emails with plus-signs in the recipient part. If it doesn’t, give your development team a demerit for me.

Use Plus Addressing Liberally When Testing

You probably have to regularly test a signup process. In fact, I’d wager that signup flows get manually tested more than any other class of feature.

Rather than jump through hoops creating all sorts of dummy email addresses, or aliases to your Google Apps users, use plus addressing. If I’m testing a new welcome flow, I’ll use addresses like:

Bonus Tip: is a special reserved domain, which you can guarantee won’t actually send anyone an email. Of course, if you need to receive a welcome email or other part of your workflow, be sure to plus-address your own actual email address!