With all the recent hacks and disclosures of email addresses that are happening recently, I was curious if its a reasonable idea to have distinct email address for every website which I have an account. My reasoning is:

  • This would give some level of protection to my other accounts if my email was hacked by limited the number of other accounts that could be accessed using the reset password feature.
  • If I suddenly receive a spike in spam, (as has happened to me recently) I would have a better chance of figuring out where my email was compromised.

Are there any down sides to doing this? Or am I overestimating the benefits from this approach? I am using strong passwords on all my website accounts and have two factor authentication on my current master email account.

  • Are you suggesting having multiple email addresses go to one account or having multiple email accounts? – Neil Smithline Nov 28 '15 at 23:32
  • What's the point of the second bullet? Who cares if one gets even more spam, and in what sense does that mean the email address is compromised? – ash Nov 28 '15 at 23:39
  • @ash - I once had an email address that I only gave to my mortgage provider get spam. When I contacted them, they freaked out as they knew from the email address that it had to be their fault. They spent a week tracking down how my email address leaked and determining what data beyond the email address may have been compromised. – Neil Smithline Nov 28 '15 at 23:44
  • I have 3 email addresses: one of them is used only to sign up to sites I don't really care about (like download sites), one of them is my personal mail (only work stuff) and the other is the Google account used for all my phone activities. This way, I've been completely clean of spam for the past 3-4 years – SO used to be good Nov 28 '15 at 23:51
  • @NeilSmithline I was thinking of having entirely separate email accounts. though now that you mention it, having multiple addresses go to a single account is an interesting idea. – mercurial Nov 28 '15 at 23:55

Isolating resources is definitely a valid and widely used method of controlling security threats.

I can think of many scenarios where these benefits of isolation would apply to email addresses, including those you mentioned.

Are there any down sides to doing this?

I don't think there's any real downsides, but I can think of a number of reasons it would be difficult for most people to derive the full security benefit of isolating their email addresses.

Firstly, you need to minimise dependencies between accounts as these weaken the isolation. For example, you'd have to avoid:

  • Using one account as a recovery email for another
  • Sharing passwords between accounts
  • Using the same domain across accounts (especially if it's your own domain)
  • Sharing an actual inbox (ie. destination for all your mail)

This creates many inconveniences:

  • It may take a lot of effort to setup many mail accounts, especially on email services you don't control (eg. gmail)
  • Having to check many inboxes
  • Having to maintain many sets of credentials
  • Having to constantly make decisions about which address to use in order to minimise risk

One common technique for people who own a domain is to have a catch-all rule that goes to a single inbox. That way they can invent an arbitrary email address every time they need one (eg. stackexchange@whatever.com) and if they get spam from a particular service they can easily block the unique address they used. This will help with the spam scenario you mentioned, but not if your account credentials are compromised seeing as all addresses will share an inbox and password.

  • This answer is valid, however wouldn't it be better to devote your energy and resources to having one email account with two-factor authentication, which would mitigate the first point of the question? – ash Nov 28 '15 at 23:38
  • @ash - you could have 2FA set up on each account. Sure it will likely drive you loony, but I think the answer discusses the trade-offs between security and convenience nicely. – Neil Smithline Nov 28 '15 at 23:42
  • @ash I fully agree that 2FA is a stronger control and should be used either way, but it doesn't superseded or negate the benefits of isolation. If for whatever reason your authentication is compromised (in spite of having 2FA) eg. via phishing or a compromised 2FA device then isolation will still be effective in minimising the impact. – thexacre Nov 28 '15 at 23:43
  • I don't understand the drawback of using the same domain for all accounts, provided they each have unique passwords. Could you explain it further? – user72066 Nov 30 '15 at 21:43
  • @SourLolita the issue is that if the DNS is compromised then all your accounts can be compromised. It doesn't completely negate the isolation, but it does weaken it. – thexacre Dec 1 '15 at 2:29

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