Ask HN: name@a.com and name+1@a.com should be considered 2 different accounts?
assuming your websites has a sign-up and you provide some free credit/usage for each new sign ups.
In gmail and GSuite accounts (not sure if other email services does the same) you can do the +1 trick.
Add +N after your username and receive the email in the same sandbox (which is actually useful in many cases).
The point is, knowing that, do you consider
user@gmail user+1@gmail user+2@gmail user+3@gmail user+4@gmail user+5@gmail
as 6 different and unrelated accounts in your db?
it is fair to _regex_ the email and remove the +1 trick?
18 comments
[ 4.7 ms ] story [ 52.0 ms ] threadThe . in a Gmail user is a NOOP.
I treat them all as unique
You can use that knowledge in constructing your anti-spam heuristics though.
If you choose to strip the tag I'd only do so when processing a new signup and make sure that the user can login with his user+tag@example.com and that all email goes to that address.
You should consider asking phone verification, or keep a credit card of file.
My default answer for most sites is that I don't trust you with my phone number (e.g. Facebook using recovery phone as an undisclosed identifier) and certainly not my credit card number in some random database.
Any pointers on how to do that?
This is absolutely terrible advice, unless 1) your site is a commerce site, and you actually need credit card information and/or phone number to do business, 2) you cannot use a payment system like paypal for transaction because you got banned for some reason, so you need to store CC info..
In any case, you actually do not need to store credit card information, because you are probably doing it wrong if you are suggesting random people on the internet also do the same on their websites without knowing anything else about what they do.
If however you're offering LOW COST items (ex: digital goods, or a free month of your SAAS), then absolutely do not filter these. Search for them afterward and contact them. These are some of your most valuable users: people who are willing to put up with the pain of creating new logins over and over again just to use your service. Find out what they love. Find out what it would take for them to start paying. They can provide intelligence far in excess of the free service credits you're providing.
If you have problems with one person signing up multiple times then this won't fix it for you. There are many other ways a person can have lots of email addresses. You will waste a lot of time chasing your tail.
I reasonably use plus style addresses to establish different identities and I generally pass on a website if their registration or other processes assumes things about my address or disallow valid characters in an email address.
I also don't try and rip-off a website by abusing their free services.
I think these patterns are generally negative for most ecommerce companies (you've priced too low, you're signing up tons of low-LTV customers at huge CPA, etc.) and good for SaaS companies that can solicit feedback or otherwise monetize their "frequent triers".
* have a separation between accounts and users. Account is the entity that pays for the service. Usually account has users associated.
* collect payment/credit card information on account creation
This way, you don't really care about user+1, because you have their payment info already, and can assume at least some intention to pay after their free tier is up.
There are many legitimate reasons why somebody while doing evaluation would create several users, i.e. I do name@a.com as well as name+testing@a.com in few services.
If you find out that too many of your customers are not willing to pay, look at it more as a business problem, trying to reach better customers that you can charge more, rather than to better enforce some account de-duplication.
I think I heard this approach from patio11, Amy Hoy or some interview on Mixergy?
The issue with the credit card verification before trying the product is that as a user, I do not like that approach.
I want to try first and eventually pay. That is the experience I'd like to offer.
For the record, I am one of those people using + as a tag, just so my username a bit different site by site but still easy enough to remember (yeah I use a password manager, but a little bit extra hygiene never hurt anyone). I’d be incredibly pissed off if sites started trying to be clever with it; I guess I could tolerate a duplicate detector, as long as it doesn’t stop me from signing up as soon as a + is detected.
If you see people abusing it, I would have a “hunting” routine and gently ask the worst offenders to shape up lest they get banned.