Show HN: Make senders work to get into your inbox (captchainbox.com)

This mostly assumes that the only one benefiting from the email exchange in the sender. If that's the case, just close your email account.

A few years ago I emailed a local freelancer I'd met in person, because I had a client asking for coding (which was more his bag than mine). I got an automated response that he was using something like this, with a link to some third party service to fill out a form and click a captcha if I wanted him to see my email.

Why would I? I just told the client sorry, I don't know anyone.

It feels like a better pricing model (if you believe in your product) would be to give it away to consumers, but take a small portion of each payment when non-trusted senders validate.

I kinda like the thought but wouldn't a simple action that sends email to the archive list for all senders that aren't on your contact list handle this? That's what I do with my phone, actually, and I might consider it for email too. Then you can manually check your archive when you have free time.

I built this for my company email, but instead of sending captchas it puts non-customer emails into a folder that I never read. Emails from customers and contacts get into my inbox, and get labeled based on their support subscription level.

Most tech companies I've seen gate and filter customer support on web not email, then only sales and external interfacing employees need external emails and the bigger problem is phishing not spam.

For my personal email I would never use this, because I myself would never solve a captcha to reach someone's inbox and I can't expect different from others.

Hi Felix,

I know the situation here in Germany kinda sucks for non-incorporated founders (or simply any website administrator trying to commercialize anything [0]), but gating imprint/Impressum behind a login wall makes it not legally compliant. It needs to be easily accessible from anywhere (that’s why most people place it in the footer), without auth or signup; and if you put it behind either Outlook or Gmail logins, you may as well just not include it at all (realistically, who’s gonna complain if you don’t include “made in Germany”).

All the best for your project, though!

[0]: Personally I’ve given up and just include my name and address on the public web in projects now, which I guess is what the federal government wanted to achieve.

This should be the case even for phones as well

Relatedly, a precursor to the Bitcoin proof of work algorithm, Hashcash [0], was created to solve this same problem.

This feels like a cool modern iteration of it.

[0]: https://en.wikipedia.org/wiki/Hashcash

Isn't this the opposite of what I want? I don't want people willing to pay getting into my inbox. Those are the people who think they can get more from me somehow. Those are exactly the people I want to not be in my inbox.

[dead]

These services pop up from time to time. All they share a fatal flaw: accepting money for email delivery turns email from a communication medium into a service. And a service carries a different set of obligations - someone paying to send an email to me expects that they are buying my time spent on reading their email and replying promptly. I am never going to sell my time like that.

What is the cheapest transaction fee crypto coin that is still redeemable for Fiat or other crypto?

I think this concept would work if taken a step further, with a new protocol that requires encryption, but only with a key provided by a block chain that cost some nonzero amount. the email server would drop message payloads whose hash wasn't on the chain, limiting DoS attacks.

When the recipient reads the mail, it starts a process of refunding that micro payment that is a 4h cycle that can be interrupted. So if you click "spam", it blocks the refund and you keep the micro payment. Anyone sending bulk emails would go bankrupt.

Anyone using email for normal purposes would only have to buy once to have enough tokens to send a few emails. Most of the time tokens would only be used inside the system, but they would need some monetary value to do their job, so they could be pegged at say $0.10.

How did you validate that this is a problem people have? Personally I haven't received any extra spam mail since LLMs became a thing.

so basically LinkedIn "InMails"

Is there not a (local) LLM that just reads your emails and puts them to spam or not? I feel like that wouldn't require an enormous model.

As others have said, this is an age old idea that has been tried dozens of times and sometimes with very big financial backing (there was another attempt on HN just a few months ago). My personal view is that this idea is fatally flawed and will never work. That said, every idea sucks until it doesn’t, sometimes it’s all about the idea in the moment, maybe right now is finally the moment for this idea? So don’t be discouraged by all us naysayers, maybe your fresh perspective in this moment could make the difference.

djb proposed Internet Mail 2000 back in the early 2000s as an attempt to solve this kind of problem without micropayments[1].

As others have said, a lot of the useful emails I get are still ones where the sender probably wouldn't have paid to send them. IM2000's fairly old-school-yet-elegant approach would probably lead to a better outcome too.

[1]: http://cr.yp.to/im2000.html

Your post advocates a

    ( ) technical ( ) legislative (X) market-based ( ) vigilante

approach to fighting spam. Your idea will not work. Here is why it won't work. (One or more of the following may apply to your particular idea, and it may have other flaws which used to vary from state to state before a bad federal law was passed.)

    ( ) Spammers can easily use it to harvest email addresses
    (X) Mailing lists and other legitimate uses would be affected
    ( ) No one will be able to find the guy or collect the money
    ( ) It is defenseless against brute force attacks
    (X) It will stop spam for two weeks and then we'll be stuck with it
    (X) Users will not put up with it
    (X) Microsoft will not put up with it
    (X) The police will not put up with it
    ( ) Requires too much cooperation from spammers
    (X) Requires immediate total cooperation from everybody at once
    (X) Many email users cannot afford to lose business or alienate potential employers
    ( ) Spammers don't care about invalid addresses in their lists
    ( ) Anyone could anonymously destroy anyone else's career or business

Specifically, your plan fails to account for

    ( ) Laws expressly prohibiting it
    (X) Lack of centrally controlling authority for email
    ( ) Open relays in foreign countries
    ( ) Ease of searching tiny alphanumeric address space of all email addresses
    (X) Asshats
    ( ) Jurisdictional problems
    (X) Unpopularity of weird new taxes
    ( ) Public reluctance to accept weird new forms of money
    (X) Huge existing software investment in SMTP
    ( ) Susceptibility of protocols other than SMTP to attack
    ( ) Willingness of users to install OS patches received by email
    ( ) Armies of worm riddled broadband-connected Windows boxes
    ( ) Eternal arms race involved in all filtering approaches
    (X) Extreme profitability of spam
    (X) Joe jobs and/or identity theft
    ( ) Technically illiterate politicians
    ( ) Extreme stupidity on the part of people who do business with spammers
    (X) Dishonesty on the part of spammers themselves
    ( ) Bandwidth costs that are unaffected by client filtering
    ( ) Outlook

and the following philosophical objections may also apply:

    (X) Ideas similar to yours are easy to come up with, yet none have ever been shown practical
    ( ) Any scheme based on opt-out is unacceptable
    ( ) SMTP headers should not be the subject of legislation
    ( ) Blacklists suck
    ( ) Whitelists suck
    ( ) We should be able to talk about Viagra without being censored
    ( ) Countermeasures should not involve wire fraud or credit card fraud
    ( ) Countermeasures should not involve sabotage of public networks
    ( ) Countermeasures must work if phased in gradually
    (X) Sending email should be free
    (X) Why should we have to trust you and your servers?
    ( ) Incompatiblity with open source or open source licenses
    (X) Feel-good measures do nothing to solve the problem
    ( ) Temporary/one-time email addresses are cumbersome
    ( ) I don't want the government reading my email
    ( ) Killing them that way is not slow and painful enough

Furthermore, this is what I think about you:

    (X) Sorry dude, but I don't think it would work.
    ( ) This is a stupid idea, and you're a stupid person for suggesting it.
    ( ) Nice try, assh0le! I'm going to find out where you live and burn your house down!

Interesting idea, one thing that genuinely confused me on the website it the slider on the pricing section, what does that mean ?

Sorry if it's obvious but it didn't make sense to me!

I like the idea of trying to make email more about human-to-human connection with less focus on automated-stuff-to-human.

The bit I don't understand, is what about where you need the automated-stuff-to-human, like, authenticating a new account? Would this just block those types of emails? Is the expectation if you used this, that you'd have seperate emails for contacting people vs accessing online services?

Interesting idea, but honest to god I don't really have that big of a spam problem anymore.

O365 is handling 90% of it on our corporate mail; my personal address (which is far older) is hosted at Fastmail and it traps nearly all the spam there, too.

In 2026, I'm much more annoyed by PHONE spam -- though Apple's "who the hell are you and why should ubermonkey take your call" feature has done wonders. (I assume something similar exists in Android.)

> Unknown senders solve a CAPTCHA or pay a fee to get in. Trusted contacts get through as usual.

Somehow I doubt this determines whether a contact is trusted.

> If a sender is willing to do a bit of work to reach you, the message is more likely to be worth your time and the sender more likely to be real.

Or they just really want to sell you something.