Hacker News Reader

Comment by kyrra | Hacker News Reader

As people said, true spammers know to just strip off the "+" in the email address. This is actually a fun reason to set up your own domain and set up email forwarding for *@example.com to go to your main gmail or whatever account, then the "username" part of the email I just set to the domain of the account I'm signing up for. So I'll use amazon@example.com when signing up at Amazon (or whatever site).

View on HN

> So I'll use amazon@example.com when signing up at Amazon

I go a little farther. I figure an attentive spammer might figure out that if I use amazon@johnsmith.net to sign up for Amazon, I may have exactly the scheme where *@johnsmith.net will work, so they can just add that to the spam list as a wildcard and pick a new address every time. So instead, I use john101@johnsmith.net, john102, john103, etc, to try and obscure my strategy and prolong the life of the domain forwarding.

Hard truth is you're not worth enough for a spammer to look for that pattern, it's a numbers game and you're just making it harder on yourself.

Also unless you're keeping a lookup table you're losing a great benefit of the wildcard. You can, and I have caught a few places, tell when a company sells your email. If I get an email from company XYZ to my email abc@example.com I know exactly who sold my email and to whom.

I agree that I'm probably not worth the effort, but if this kind of domain wildcard strategy were to become more popular it is entirely feasible for a rudimentary machine learning algorithm to detect its use.

> unless you're keeping a lookup table you're losing a great benefit of the wildcard

That's true, I don't keep a lookup table per se, though I do have a deleted items folder that I could look back in. I'm not sure what I would do, though, if I knew what particular company sold my email address? Send them a nastygram they will just ignore? I just block the address and move on.

I think a typical spammer doesn't care much about such users, but if given given a choice they would rather avoid such users.

AFAIU, most buld spam is targeted on gullible or vulnerable people. The spam is often terrible on purpose.

Sophisticated or targeted attacks are a different category and they may be a good reason to prefer something non-guessable.

I just have a entire domain for the purposes of spam. Anything sent to there ends up in my bulk folder. I use amazon@domain.com so I can tell who sells my email or gets hacked. Never noticed someone trying to send a email to any addresses I haven't previously used.

> Never noticed someone trying to send a email to any addresses I haven't previously used.

At least a few years ago, I noticed a lot of spam to <random first name>@<my domain> -- i.e., completely made-up addresses that I had never used. Since messages sent to those addresses were guaranteed to be spam, I started treating them as free training data for the spam filter.

I don't know if this still happens, though, because I haven't looked.

This is currently happening to my email domain. Gets rejected as it doesn't have a valid hash (recipient name), but the logfiles are full of <3 letters>@mydomain.com and <english_word>@mydomain.com rejections.

Yeah, this is an age-old issue -- in the early 00s, my mom got a domain and used the email <first_initial>@<domain>.com. She gave up battling the deluge of spam after about a year. We looked through the logs, and saw that her next choice of handle was also getting tons of spam, too, because it was also short.

I do the same thing. I use whatever@domain.email. The addresses are temporary if I want them to be and I can automatically lock the senders to a list that is either automatically learned after x days or manually curated. I've seen some 'marketing' mail get filtered but no hacks yet.

I’ve got amazon@domain.com email for my domain and I’ve never created such an account, much less given it out. Without some uniqueness in the username, I’m not sure you can tell a company sold or lost your data.

Spamming is a numbers game. I kinda doubt enough people are using this scheme to make figuring this out worthwhile for a spammer.

I've wondered about this with big companies like Facebook, Google, Amazon, etc. as well as behind-the-scenes spyware/ad firms who are all probably very interested in linking my identity across user accounts, email addresses, device fingerprints, etc. I've hoped that there aren't enough people doing it (yet) for these orgs to find it worth the effort.

There very much are companies doing this and selling it as a service...here's an API that you can query with a piece of contact information to retrieve all sorts of additional information, including hashes of alternate email addresses, mobile device ids, social media profiles, and plenty of other stuff: https://platform.fullcontact.com/docs/apis/enrich/person-ins...

At a certain point -- probably the moment it becomes a business unto itself -- this kind of data collection should be subject to all the same rules we've come up with for credit bureaus. It should be a legal requirement that I can get the entire profile they have built for me.

I was wondering specifically if they have special cases to identify such "personal" email domains and use them for record linkage.

It seems like an obvious thing to try, but maybe not worth the effort of implementing it, given the high risk of false positives and the low % of people who actually do stuff like this (not to mention they're probably not people who click on ads anyway).

Given the sheer amount of money involved, I believe it is likely that there are players in the market who are far more capable than we give them credit for.

I kinda imagine that spammer go for low hanging fruit. So spammers won’t bother with defeating a catchall domain forwarding, as it’s unlikely to give them returns. Although a motivated attacker might decide to try to send interesting phishing.

What do you use for email hosting? Ive tried to do something similar but most places have a limit for email addresses even with paid plans.

Fastmail does not seem to have any limit listed. I have not tested any extreme case since I just use a wildcard.

well, you could turn it around and use + addresses everywhere, so that any legitimate response must be to one of your + addresses. then treat anything without + as spam.

That makes me want to use an email address of the form +myname@mydomain.com, just to see how websites would handle stripping out everything starting from the +.

The + is also useful for knowing who sold your email address on or was responsible for a data breach. If I start getting spam to <my name>+hulu@gmail.com, then I know I could chase down Hulu on Twitter for an explanation.

I do a similar thing, except that the email is actually hosted at my domain rather than being forwarded, and that I have a list of email addresses that I accept and reject all others; if I receive too much spam at one address, I disable receiving at that address.

I have found this to work; I hardly receive any spam at all, and do not need any separate spam filter.

I've run into at least one domain that blocks their own name in your email; that was fun.

Didn't you find you got a deluge of spam to generic addresess like admin@, info@, offers@ and so on? I tried this, although it was probably about 15 years ago now, and reverted it because I got about the same amount of spam as genuine emails.

Although hardly anyone uses yahoo mail anymore, they actually have this feature built in. Basically email aliases.

Note that you should only do this for maybe 6-18 characters, some sites will test send an email to [30-100 character random string]@example.com and see if it bounces - if it doesn't, it'll suspect that domain to be some spammer with a catch-all email inbox and block it.

That's a terrible approach, plenty of valid, legitimate non-spamming domains use catchalls of arbitrary length for all sorts of reasons.

Additionally, sending a test email like that might also get the sender placed on a black list for triggering a spam trap inadvertently.

That's a worrying strategy because there are many reasons for using a catchall. Example: one email per site to track companies selling personal data, then maybe bounce that single email address.

Do you know any site blocking domains with a catchall?

Yeah, if you have a domain of your own the sensible thing is a catchall, use a different address everywhere and block the ones that spam.

Do you know what sites do that? I have my own domain and I haven't seen anybody do that. The obvious solution is to configure your mail server to only accept usernames before the '@' that adhere to some rule which only you know. Like checking if it is a palindrome or something obscure like this.

I watch multiple corp's mail logs extensively, this is not even remotely a common thing.

Worse, I know at least 5 or 6 people personally, which do catch all. It seems like a very poor method to reliably catch spammers.

Max local part size is 64 octets. So 100 chars would be out of spec.

Reply on news.ycombinator.com