> if you run a full domain you can use emails as one-use affairs

or, if you use a service that lets you generate aliases, like gmail's "+", or a service like mailinator.

The problem is that the attack vector of email addresses is they are sometimes used as a username, and therefore contains more information than what is strictly required (for the purpose of a username). Leaking the "real" email address not only leads to spam, but allows a more dedicated attacker to use that email address as a starting point on a different site, or hack the email address altogether.

And with sites increasingly blocking disposable email addresses like mailinator, or disallowing email aliases, the problem can only get worse.

Having your own domain is cheap. Generating an email that’s a function of the target website is trivial. I’ve done it for 20 years.

I can confirm the source of every email breach that contains one of my addresses.

Yep, I do the same. I typically use <sitename>@sites.<domain>.<whatever> for website logins (stored in my password manager, so I don't need to think about it to login), so that if my password ever leaks, I know where it was leaked from.

sadly using elite hacking skills this is easily circumvented

    p0wn3r $cat  testerm
    [email protected]
    [email protected]
    [email protected]
    [email protected]
    
    p0wn3r $cat  testerm | sed 's/+.*@/@/'
    [email protected]
    [email protected]
    [email protected]
    [email protected]

and so if you set up your email filters right, you can find out who is doing this sort sort of "hacking" to get your real email address. What you do afterwards is up to you.

By definition, if someone is offloading your data to a 3rd party and they sanitise the addrs, then you can't tell.

The "+" is not limited to Gmail, it's standard. The problem is many services with fancy mail validation don't accept it.

Does Gmail allow sending from the + addresses? There's quite an issue if somebody contacts you on that address but you reply without the alias.

They do allow it, but it’s a pain to set up for each + address, especially on iOS.

I have not find a way to send email from Gmail, using either the web interface of their SMTP server, from a custom username (left side of @ symbol). I have a custom domain using Google Apps, but to send mail I use a third party SMTP server to customize the username portion of the From field.

I've never had an issue using a different email for support, I always mention that I own the domain or email suffix and they can verify that if they want to (though nobody has so far).

I'd forgotten about the gmail trick. You're certainly right about that. Though I will say one thing: I've not been hiding my email this past decade and—as far as I know—it has not bit me.

> you can use emails as one-use affairs [..] what's the point? It only saves you from journalists, not from a motivated attacker

Can you explain this claim?

If you generate your single-use email addresses wisely, then you should know that the one you gave to - say - Marriott should only ever receive emails from Marriott.

If - say - Marriott gets hacked and that particular one of your many different email addresses leaks, then:

a) you'll find out that address is burned just as soon as anyone other than Marriott uses it (you immediately generate a new one, give it to Marriott, and stop accepting any mail at all on the old one)

and

b) if anyone other than Marriott uses it, you know immediately that that message can't be legit.

c) chances are that all your incoming phishing traffic will arrive at mismatched addresses. Makes it even harder to fall for it in that moment of mental blackout.

But if someone phishes you on [email protected] you're probably more likely to imagine it's legit. Swings and roundabouts.

No-one would know that [email protected] is an email address you can even be reached on, unless it leaks out from BankCo.

ADD: and of course, you aren't really going to stick +BankCo after your real name to generate an email to use with BankCo. You're going to give them something generated like you'd generate a password - "[email protected]" or similar - so if anyone finds out that particular email address for you it doesn't tell them with whom you use it.

But that's a big if because phishers will always aim for the weakest individuals in the flock.