Enable search and notifications for email addresses using the "+" syntax
A lot of people use a syntax such as email@example.com where foo is a unique identifier for the site. They do this so that if they begin getting spammed, they can identify the source their email came from.
At the moment, HIBP treats this is a totally unique email address so if I've search for the parent email address without the "+" syntax, it won't be found. This idea is to ensure that searches and notifications recognise the syntax and return addresses that are logically still the same account.
One thing HIBP would also need to do is specify which account alias was in the breach or paste. For example, I would want to know that it was firstname.lastname@example.org that was exposed in the XYZ breach.
Edit: Just to put the value of this into context, I've just run some stats on the Adobe breach. Of the the 152,989,508 rows in the dump, only 49,905 email addresses have a "+" in the address so that's 0.03% of entries. That number is also a bit high as it includes junk entries. I'm definitely not ruling this idea out - it's still planned - I just wanted to give a sense of how useful it would be.
Edit: To add to this idea, Robert's comment about a period in the email is also very valid. I'd want to be very clear about the ubiquity of this practice across mail providers, but it's certainly a good suggestion and worth further investigation.
Chris Zuber commented
Some means of normalizing emails would definitely be a great addition. Not just for the plus, but also for case and dot variations.
Having managed a website with a lot of elderly users, I know how often email addresses can be something like "First.Last@provider.tld" and that these are often inconsistent in case or dot usage.
Alex Guenser commented
I have been migrating some of my site information to using the + syntax, so i can better trace who gets my email from where. But I am very wary to use this too frequently, in case I can't trace now automatically if my email and password has been leaked!
St. Mueller commented
Like others I have been using Yahoo's disposable addresses frequently. This useful mechanism made good sense because it has kept my main email address save so far. The down side is that I cannot possible imagine how to test all 141 addresses manually through HIBP and I do not know enough about working with the API to do it on my own.
Ever since I first heard about HIBP, I was hoping for such a possibility and I am hopeful that this discussion leads to some useful outcome. My first idea was to feed a list of email addresses into HIBP and that the results are sent back to these email addresses. I am sure there are things that I am overlooking but it seems reasonable that mainly the owner of the address in question should be the one informed.
Many, many thanks to the people behind this valuable tool!
Tom Ryder commented
Please do this; it would be very useful for me (i.e., +1). I like the idea of normalizing the emails into some canonical form as they appear in the databases.
Best change for HIBP commented
I'd love to see this. Maybe this year ?
Also - how many searches / subscriptions are for e-mails with +foo in user names? Maybe this will be a better argument for implementing?
Not that hard? commented
What about just normalizing emails? There are libraries out there that can do that with all the different rules that exists (ie + for gmail/outlook, - for yahoo, remove "." for gmail, change domainname for googlemail.com/protonmail.com (pm.com) etc. Example libraries:
Lot of good comments and suggestions here. There is just one thing here that I miss. For the proof of the email address to support this you could do an e-mail verification. I understand that getting the UI right for people to specify whatever their settings are would be tricky, but let's say you could select "I have e-mails with plus suffixes", then the verification e-mail would be sent to `email@example.com` and if you are able to verify it, at least the notification for new pwns could be working. Of course the variations would have to have their own select box or something, but that allows for incremental feature addition when people would request their particular settings. That would also show how many people actually care about anything else than "+suffix" format without the need to implement everything at once. Of course I would also love the `breachedaccount` API to support this, but I understand that is more complex to achieve.
One more thing that I have noticed here is that when Troy run the stats, only the plus sign addresses were calculated, not the .dot syntax or other suffix/prefix combinations. And it is fine, it is as impoosible to get better stats as it is to implement this completely as if you can do one, you can do the other. However that proves that partial, temporary implementation is better than nothing.
I think handling of these is important. I've actually used various iterations of a Gmail email address with different period placement to give the appearance of unique email addresses. This is usually for opting out of sites that publish my information using multiple versions of my name (such as whitepages.com, peoplesmart.com, etc.) where they often only accept one opt out request for an email.
An easy solution to the problem of periods used or not used at any location in a username would be to simply do a use do a comparison of email addresses without any periods. In other words, if replace(SearchedUsername,".","")=replace(PwnedUserName,".","") then there is a match. This could be implemented such that it applies automatically to email domains known to support this (such as gmail.com), and otherwise only when the option is checked by the user. That way, you're not checking every possible iteration. It might be more efficient to have a second field in the database for a "period-less" email username, but the trade-off would of course be more storage.
Similarly, the + system could be implemented in a similar way, where the plus and everything after are stripped off for searching purposes. I've never used that system, but have been looking at it recently. It seems to me that, in most cases, the + tag is not really needed, as the sites the email was used on should often bring that into context. But, as another user suggested, you could also allow searching of the + tags as well simply so a user who received a positive result on their base email username could then check using specific tags they use.
Without reading the whole comments here (just the first page, sorry), there really is no way to do this. The Postfix MTA allows multiple, configurable delimiters. And you can never be sure that a delimiter character IS a delimiter. I can create an address like this: <"Eat @ Joe's One-Stop + Get Gas"@example.com>, and it would be perfectly valid. The localpart can contain ANY printable 7-bit ASCII characters from decimal 32 to 127 inclusive; the limit is max 63 characters. Don't take my word for it, see RFC 5322.
Steve Work commented
I get the complexity concern, and that '+' and '.' don't cover the bases (qmail used '-', etc.), and that broad-population email sampling shows low use. Sounds like Troy gets that the population of HIBP users isn't representative so broad numbers don't necessarily apply, and that it's pretty easy to know the full set of aliases at my end and check them all. But it sure seems like there's middle ground between flat "no" and covering all possible cases deterministically. It might be fun to work through some of them.
I know this will likely never get implemented, and that using aliases to prevent spam is easily circumvented by spammers stripping it again.
But it was such an innocent feature to use, without any consequence, and HIBP is the first time I've had an issue with it, and now my security is slightly worse for it. Is there no middleground?
I use the plus syntax for all my logins, it'd be great to have this supported in HIBP
I'd love to have this implemented to filter out '.' and '+foo' for email domains that allow this, specifically @gmail.com
Wouldn't it be quite easy to follow a recipe like this:
In a breach Troy could do the following for email addresses which are known to implement such a decoration scheme:
- add another record where all decorations have been removed but don't count it to the number of breached email addresses
* found in a breach: firstname.lastname@example.org
-> add also email@example.com as kind of hidden record for breach, too
I understand there is some complexity involved here and email decoration might not be used by many, but those who do it on purpose, do it with something in mind.
there's also a million ways to do this - e.g. not using a syntax at all or just pre-fixing or addending the service name. not sure how you could accommodate all of them.
I just voted in favor, but I understand Troy's perspective.
better enable .dot syntax for google mail accounts!
I understand the problems with complexity of the + (stripping useful information, etc) but what about periods? If my email is
I can put periods anywhere in that email address and they will all resolve to me.
You're not adding a suffix, just inserting periods. How complex would it be to detect variations like that? Perhaps a way for a user to opt-in, noting "please check for period variations on my email address"? That way you're not scanning an astronomical number of permutations against a list. For example, knowing I've opted in and my email starts with "pr" look for all breached emails starting with the letters "pr" and strip the periods from them in a temporary list, and compare with mine?
The reason I ask is because I've used a lot of period variations and can't always remember the way I've used them. I only got notification of a recent breach from a vendor themselves, not HIBP. I could add as many as I could remember to the HIBP mailing list, but don't want to stuff your database with that if this will be added at some point.
IT should work now! commented
Maybe as an alternative you could allow a 'batch' search feature, where I could load all my <name>+<website>@gmail.com addresses and a report with a matched results summary for each?
The onus would be on me to maintain my list of addresses (not hard, a CSV export from 1Password would do it).
No change to status as of now, complexity remains the same as does prevalence of use.
This feature is by far the most wanted feature for hibp on uservoice.
Not many people use email filtering that way, but almost every people using it are tech-y people who use your website and services.
It may not be significant overall but I believe it's a more significant trend within your own users.
What are your thoughts on this feature as of now?