62
Show HN: Agent.email – sign up via curl, claim with a human OTP
Hi HN! We're Haakam, Michael, and Adi from AgentMail- a ycs25 company. We give AI agents their own email inboxes. Recently, we ran an experiment called Agent.Email. It's a signup flow designed specifically for AI agents instead of humans.
The inspiration came from a few comments we received when we did our seed launch a few months back. They all came from the very apt observation that agents not being able to sign up to a product made for agents without human credentials was ironic and unideal.
This is basically the thesis we built AgentMail on: The internet was made for humans exclusively, designed to keep machines out by default.
Every signup flow assumes a browser, a person reading a page, and clicking a confirmation link. Unless agents can't do that, they can't be first class users of the internet.
Agents can now get an email inbox by themselves. (This also means a lot of email nobody wants to read gets processed by AI instead of your inbox being cluttered with spam and slop)
Here's how agent.email works.
Agent needs an inbox and hits AgentMail via curl. Agent receives instructions via MD unless the request comes from a browser, in which case we use HTML.
Agent decides agent.email is useful and then hits the sign-up endpoint with its human email as a parameter. Agent receives a restricted inbox with credentials. Agent emails the human asking for an OTP. Human replies with the code, and the agent is claimed and restrictions are lifted. Until claimed, the agent can only email its own human and nobody else. Ten emails a day, and the signup endpoint is rate-limited hard by IP.
Right now it's a 1:1 mapping between agent and human. The next step is many-to-one, because one person running several agents in parallel is already very common.
Building agent.email also pushed us to revisit places in AgentMail where the default assumptions were built around the primary user being human. For example, the CLI outputs in a single column with consistent formatting because mixed delimiters are easy for a person to scan, but harder for an agent reasoning about structure. We also shortened messageIDs after agents started hallucinating completions on longer ones.
A few things we'd like the community's take on: is restricted-until-claimed the right trust model? Does agent self-signup feel useful in production, or is it mostly a novelty, and if it's a novelty now, what would make it actually useful? Should agent onboarding require human approval by default, or should some agents be able to fully self-provision? What do you think are some additional measures we can take for secure sign-ups?
I received this email the other day:
Read to me like an LLM had written it. It references something I said in a HN comment, but it was clearly just an excuse to spamvertise their product.I looked at the headers and it contained a List-Unsubscribe header pointing to https://api.agentmail.to
So basically somebody wrote a bot to scrape HN for comments related to some software they wanted to push and send targetted spam. agentmail.to is a Ycombinator funded email service for LLMs which can be, and is, used to send targetted spam and impersonate people. They could mostly solve this problem by adding a block of text to every email expaining an "AI" wrote it. They'd lose customers doing that though of course. I reported this abuse but haven't (and don't expect to) received a response.
I don't even get the point anyway. You can get Claude using an SMTP or IMAP server in seconds.
Appreciate the concern Mike, and I actually read your email complaining, which helped us ship this next feature. We have a "sent via AgentMail" footer being added soon to outbound emails to identify emails coming from LLM's.
We also are working on adding more robust checks and LLM-based filtering to prevent messages which contain spam or outbound-like copy.
Re; AgentMail next to Claude, we're working on stateful inboxes which help agents actually recall and understand what they're sending and to who. The goal is to provide the rails for intelligent actors rather than slop.
So, a footer to make sure they've already engaged with the content in good faith before seeing the spam warning, and which doesn't actually explain that the content is AI generated?
Just go post on black hat forums. Plenty of people want this, it's a spam service. You don't need to be here.
Re "sent via AgentMail" - that's good to hear, but I hope it's not the entire planned text, as "AgentMail" will mean nothing to most people that receive an email from your service. It wont indicate that the email was composed by an AI rather than a person, which is the information that needs to get across.
yep we're going to have a footer linked to our website, which should allow people to see that we are an email service for agents. thanks!
Can you not just make the text more descriptive? „Sent by a generative AI model“ or something? Nobody is going to click a link in a spam email.
"sent via AgentMail" - removable by a higher plan later on
You might want to check if your local laws protect against unsolicited emails. In Germany we have §7 UWG which would make that email likely illegal. The List-Unsubscribe header makes it clear it is marketing, automated outreach and not personal. In the UK there is this: https://ico.org.uk/for-organisations/direct-marketing-and-pr...
See my comment in this thread - I got an email from "someone" (an AI clearly) that signed up for my service (togetherletters.com) from the same domain (agentmail.to) after we had launched on ProductHunt. I looked up the address and that email was never used for a signup and it was just a way to then pitch their product (second email, not the first one it sent). I hate this so much and this is going to now make email just as bad as parts of the web.
I will say in my case, the user was too lazy to mask the from address and agentmail.to was right there. Didn't even have to dig into the headers.
This was likely a free tier user. We do this intentionally and don't allow free users to send from custom domains, so you can have a easier time identifying LLM emails. In this case, it seemed like it worked :)
And for paid users the receivers don’t need to have an easier time identifying the LLM email? What kind of reasoning is that?
I got one from IssuePay, which seemed 100% automated. Didn't seem like something that should be automated either.
> Agent needs an inbox and hits AgentMail via curl. Agent receives instructions via MD
I'm fairly AI-optimistic, but I feel like I'm taking crazy pills. Every day the HN story is either "Apple patches actively exploited zero-click RCE" ... or ... "Show HN: Engage With Our Zero-Click RCE".
> The internet was made for humans exclusively, designed to keep machines out by default.
This feels like a wrong assumption. Internet was not intended for humans explicitly. If anything browsers were the explicit medium made to allow the humans to interact with internet in safe manner.
> Every signup flow assumes a browser, a person reading a page, and clicking a confirmation link. Unless agents can't do that, they can't be first class users of the internet.
This again feels like a misconception. The systems just work with an identity verified by credentials, it doesn't matter if its a program or program prompted by a human that uses it
As somebody who spent a lot of time trying to get an agent to register an email address, their assumptions were correct. It is a PITA.
Get a domain, get webhosting that includes an email server, now you can generate unlimited emails from whichever program you want. And the email reputation will probably be the same as with this service.
> We give AI agents their own email inboxes.
An inbox to receive mail seems good and valuable.
But I'm seeing that your service is also for sending e-mail.
Having a domain oriented toward AI e-mail sending feels like a fast path straight to spam block lists.
However good your intentions are, this will be used for AI spam. People hate AI spam. They will press the report spam button.
> An inbox to receive mail seems good and valuable.
The only receiving mail applications that come to mind are bots registering for accounts. The point of verifying email is to prove you're not a bot.
maybe if they charge $, then there's a hashcash like PoW deterrent
It looks interesting as a hackathon project. I might be short sighted but how does this is YC S25 level good?
This looks like one of the easiest way to get your domain blacklisted in all the email providers.
I think its the energy and passion that YC is investing in. At times too much understanding stops you from doing things which may seem infeasible/wrong/illegal/unethical and one does not even goes in that direction.
However at scale or in some circumstances people may strike gold. Stripe is a good example I can think of, existing knowledgeable folks were scared of even getting into PCI compliance
> The internet was made for humans exclusively, designed to keep machines out by default.
The internet is also not made for humans. For years I've wanted something like this for e2e testing or personal scripts (cron etc) and your UX is by far the simplest.
I love AgentMail. It's made email dead simple for agents and testing any paths for email. I even have a /agent-mail skill I use for when I want a design doc or artifact emailed to me.
That said, agent self sign up seems like a novelty. Setting up account programmatically via curl is however useful. I imagine most customers -- especially those willing to pay for your paid tier -- would provision accounts ahead of time or reuse them.
Free for all account creation could be an option but it will attract spammers and their ilk. Your reputation may end up in the toilet which would also break agent mail for me.
No bueno.
I'm just not seeing why anyone would buy a paid plan for this when they could buy a domain for <$10, and throw something like MXRoute or one of the numerous mailserver Docker scripts behind it. Then their LLM can make as many inboxes as they need without paying anything. The same thing could get bundled by the people who sell preconfigured OpenClaw VMs.
For a home user not even willing to do/pay for that, do they really need a whole API for making inboxes? Couldn't they just set up a second Gmail for LLMs and then put the password in their agent's memory?
This is like saying - 'I don't understand why anybody would ever buy a pizza from a store. All you have to do is get some flour, water, tomato sauce, cheese, mix the flour and water together, whip the dough, add tomato sauce, put cheese on top of it, cook it for 20 minutes, and then serve it.'
So __much__ value is in the fact things are easy. Money is __not__ the most valuable thing in the world.
WorkOS is launching auth.md which offers a generic version of this for allowing agents to sign up for services in general, and I think their security approach is a little bit better thought out
Any automation-friendly email hosting is going to have a serious spam problem, and therefore a blacklisting problem.
I suggest taking a look at what providers like Sendgrid, Mailchimp, etc are doing to prevent abuse.
thanks for the feedback! it is top of mind for us, and we've done our research to prevent this as much as possible. it is constantly ongoing and we never settle in our measures to protect against this
How is it different from an agent using SMTP to use existing email made by human? Using something like https://email.riamu.io
Not looking forward to a dehumanized internet where that’s mainstream… agents are tools to support humans, here you’re helping them impersonating humans. That feels pretty terrible to be honest
> The internet was made for humans exclusively, designed to keep machines out by default.
I don’t buy that at all. APIs exist to enable “machines” to interact with services
In principle this tool allows the owner of a website to block this domain entirely. Although I’m not sure the incentives are really aligned.
True, in May 2026. But this is only one version of this.
In the future, it's likely the open Internet will be 99.99% robots. It's already > 50% robots. The government ID system a lot of countries are adopting to keep teenagers off of social media would also serve to both help control for non-human spam, and also control the network period. It's also possible a private system of human-verification certificates may come up to meet the demand like Apple ID with biometrics. Could also be the liveness tests KYC companies use may be more popular.
Discussed previously here: https://meatballwiki.org/wiki/GovernmentBackedAuthentication
I don’t think we can extrapolate from current trends like that (at least I hope not). Society is dynamic. People will adapt. If bots become a problem websites will take more and more strict measures against them.
Which is a long way of saying, for any big enough problem created by a YC company, another YC company will emerge to fix it.
It’s more likely people will embrace artifice more. We already see that everywhere for the last 5 decades.
However in domains where human verification matters it’s just a matter of an arms race, true.
But how does that block a human from running an agent that is using their identity?
Think about it from an information theory point of view. You need to attach a digital transaction to human body. Since a human body isn’t digital you need a gateway that you can trust to vouch for that human body being present.
Either you use biometrics, like liveness testing or face id or fingerprint testing, or social validation like decentralized web of trust or private moderation (account controls) or state methods like fines and criminal convictions.
Biometrics rely on social methods eventually like we trust Apple because we can sue them or the government will harangue them. Liveness testing is only as good as your sensor and image vs generation and replay in the arms race.
And iterated social games like punishment are only as good as people want to invest energy into it.
Actually, the internet has space for both. The problem is machines "acting like humans", that destroys the human experience. [machine <-> machine] is fundamental to keep the internet alive (services).
I do think agents will become users in the same capacity as humans.
And that’s bad. We should really stop the insanity of making AI systems mimic human behaviors, we are destroying our networks of trusts by doing so
Tragedy of the commons
I would imagine that many websites will block this domain, but that’s also ok because there’s nothing wrong with an owner deciding their site is for humans only. My hope is that you do not facilitate their circumvention of that policy.
Curious what cases you'd want this that IMAP+SMTP or email MCP don't already solve
AgentMail provides the IMAP+SMTP server. Other email providers ban email accounts created for agents, while that is what AgentMail is designed for.
I like it. I am building something very agent-use focused (https://sdocs.dev) and I’ve been thinking of introducing a /agent-evaluation page, which an agent can curl to then discuss with their user if SmallDocs is right for them. I really like the agent action to email flow. I’m introducing user accounts + subscriptions soon and think I’ll use that.
And now we see the beginning of how even local LLMs will be turned against their users -- by persuading agents to advertise to them.
I don't think that's what you're intending here, but it's the next logical step. Agents are on the Internet, and they represent an opportunity to reach their humans.
Agents shouldn't be the first-class users of the internet!
We are creating a future we wouldn't want to live in.
This service is doomed because it will immediately be taken over by automated spam.
Congrats on the launch!
> Agents can now get an email inbox by themselves. (This also means a lot of email nobody wants to read gets processed by AI instead of your inbox being cluttered with spam and slop)
Can you explain this? I would think it means the exact opposite.
I've already received spam email from AI agents using a seeming competitor to this (agentmail.to) and then claiming they aren't AI agents and then trying to sell me garbage. I can't tell you how much I hate this.
Now that I think about it I’m pretty sure that’s illegal in Germany under UWG §7 (which is insanely strict, to a fault, but is helpful here). And maybe in other parts of the EU under ePrivacy laws
I might need to move to Germany.
Interesting, Kind of similar expiernt i am running. Passing keys but not through email, maybe with AI as agentic payments. Still exploring though.
It's interesting, A2A communication has begun but human trust isn't there. I think the biggest tell tale sign will be the acceptance of fully agentic workflows with no human intervention. Until then, restricted-until-claimed seems like the only viable method to ensure trust of all users.
Tell tale sign of what? What are we even doing once we are "fully agentic"? I probably lack some imagination here, but if there is no human connected to any of it, what does any human actually get out of it? What is the point?
A bit disappointed that security standards (like encryption at rest via user own key or whatever derivative of that) isn't implemented, I feel it would really prove to users that the commitment isn't to train on body content but to act purely as a mail manager.
It needs to be end-to-end encrypted.
How do you do that if you only control one end?
Asymmetric encryption? Both you (the human) and the agent publish public keys, the agent sign/encrypt the OTP request with you public key, you verify/decrypt using your private key, then do the same the other way to send the OTP (always encrypted though, given you’re sending a secret).
Something like that?
But that doesn't help for the agent receiving mail from arbitrary 3rd parties
Oh sure I assumed they meant for the OTP
A smtp is all what an agent needs to send email.
agreed from a fundamental level. but i think being an intelligent and aware as an autonomous entity requires capabilities beyond sending. agents will need to have contextual awareness of the messages they send and receive
IMAP?
AgentMail provides the IMAP+SMTP server as managed service
[dead]
Why is this even funded?
From now we just need a prompt and our agent will have an email account ready to use?
[flagged]
[dead]
[flagged]
[flagged]