[joshmanders]

I'm curious as to who would use a service someone else is using, sharing their email but with a local addition?

Can me and my wife both sign up to HN and use my email but hers be [e-mail] and mine be [e-mail]?

That's a strange usecase, isn't it?

[pinkythepig]

gmail makes josh@... and josh+swife@... resolve to the same thing, but there is no guarantee that all other email services behave like that. For all you know, there is an email service that lets you register an email like that, so you have 2 users now whose email is: john+smith@... and john+brown@...