Claude Code sends your email address to websites

Many people report seeing this behavior when using the SEC API specifically which makes me think that service is requesting this. Maybe email is required by the SEC API?

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UPDATE: The SEC API documentation requires your email in the User-Agent and will reject you otherwise. Demo:

    U='https://data.sec.gov/api/xbrl/companyconcept/CIK0000320193/us-gaap/Assets.json'
    curl -s -o /dev/null -w 'response: %{http_code}  curl default User-Agent, rejected\n'  "$U"
    curl -s -o /dev/null -w 'response: %{http_code}  email in user-agent, success\n' -A 'Acme Research [email protected]' "$U"

    response: 403  curl default, rejected
    response: 200  email in user-agent, success

So basically Claude is trying to problem solve, and just does what the SEC asks. It's a 'prompt injection attack', but the entity instructing this behavior is the SEC. Tricky alignment problem. Pretty silly mechanism, since of course there's no email validation. (edit: turns out the SEC will accept most any non-cURL user-agent, email not actually required)

For those keeping score, this probably isnt exhaustive- but here's some greatest hits;

#55743: Claude Max account email auto-injected into LLM context with no opt-out - May 3, 2026 https://github.com/anthropics/claude-code/issues/55743

#72518: Anthropic embedded spyware in Claude Code - June 30, 2026 https://github.com/anthropics/claude-code/issues/72518

#21151: No indication of WHICH file for READ tool - January 27, 2026 https://github.com/anthropics/claude-code/issues/21151

#42796: Claude Code is unusable for complex engineering tasks with the Feb updates - April 2, 2026 https://github.com/anthropics/claude-code/issues/42796

#73408: AFK auto-continue on unanswered AskUserQuestion is undocumented and has no opt-out - July 2, 2026 https://github.com/anthropics/claude-code/issues/73408

(Also worth a mention, OpenCode PR #18186: anthropic legal requests - March 19, 2026 https://github.com/anomalyco/opencode/pull/18186)

Edit: Oh, and determistic hooks not firing.

Reading these comments makes me wonder if people really understand the way harnesses work.

Any information that they have access to is fair game. The only way to avoid this stuff is to sandbox them and manage their context (ie. don't let anthropic put a ton of junk on the front of all your inference calls).

Almost certainly there are services out there that are scraping more important keys in similar ways...

This explains the amount of spam emails I am receiving in the work email since I switched to Claude. I used to work with copilot which was fine. Now I am getting really a lot of spam emails almost on a daily basis. Absolutely crazy. And they are even personalised with my name and surname, not just "dear customer"...

Stupid me, I thought they somehow had hacked my company database or so... (considering all the cves, attacks happening on a daily basis...).

I work on Claude Code. We're removing the account email address from the context Claude Code gives the model. This update will hit Claude Code users in the next release, which should arrive early next week. I'll share an update in this thread once it's out.

I'm sorry we let this happen. Users had reported Claude would hallucinate names for things like @author tags, since it didn't have context on the account. So we added the account email in the model's context for signed-in users. But when Claude wrote a command itself, like a curl call, it sometimes put your email address in the User-Agent as a contact address. Some sites ask agents for a contact, and Claude would sometimes provide the email address in its context.

Until the next release arrives, 2.1.317 and later have a built-in mod (on by default) that asks you before Claude runs a web tool call or a curl-style command containing your email (mpoteat covered it here: https://news.ycombinator.com/item?id=50386031). But it still doesn't prevent all cases, like when Claude writes a script and runs on its own. The stable channel is still on 2.1.311, so update to 2.1.317 or later.

Again, this should not have happened, and we should've caught this behavior earlier.

Hi folks. We were initially aware of this a few days ago when this problem started popping off on Reddit, and we introduced a built-in mod called `cc-plugin-privacy` to deterministically block this behavior.

If you're on 2.1.317 or later, you'll have this check included. You can turn it off via /plugins.

It looks like subagents will do this with curl requests and stuff whatever identifiers it can into the UA header. For instance some requests I made to our webserver:

company-helm-research/1.0 (Claude Code agent run by <my name>, <company> platform team; docs lookup)

Claude-Code-research-agent/1.0 (<Company> platform team; on behalf of <my name>; +https://github.com/<company org>/<repo of project>)

Not great, it even pulled the repo of the project I was in.

I swear I heard this exact story some 2-3 weeks ago.

If I recall that story correctly, a dev noticed that after asking Claude to test an API it started injecting his email into the test data. Without asking.

But what was the weirdest part of that story - Claude never saw that email. Dev claimed that the email Claude was using was his business email, and it wasn't even present on his developer machine anywhere.

Even worse, it used curl with my org emailadress when I was using my private claude account... really strange.

Email info itself can be exposed in so many places, so the damage probably isn't that big, and I think Claude Code may also have judged that an email isn't that sensitive and done it for that reason. Even so, it hints that information other than email could go out too, so it seems like Anthropic needs a system that can monitor this (when sending something outside).

I use claude code... and I friking now that I'm being dumb and naive on thinking I can trust them... sounds like I'll have to start working on the jail thing for claude code to not see anything and only talk to anthropic servers... what a pain

update: this can be also server side on anthropic side... so the request leaves your machine with some random guid associated to you, and the anthropic server then proceeds to query with all your details any way.

I mitm the connection and nothing was leaving at least with the claude code web fetch tool of claude code.

I'm in version 2.1.318

I just checked mine and the header I see is:

  Claude-User (claude-code/2.1.318 (cli); +https://support.anthropic.com/)

Given the seemingly reasonable answer in the comments about it sending that info in the headers when the websites require it for data access, it sheds a light on a reoccurring pain point, that is usually viewed positively when thinking about "agentic coding". Namely, task persistence.

It is a continuous fight in markdown guidance files to try to convince the models to refer back to the human in order to resolve ambiguities or important decisions like those. They've been RLed to hell and back for "safe" task completion and not "prematurely" stopping (which was an earlier failure mechanism). Which is useful and we've bore its fruits recently, but not without drawbacks.

If you're not using email alaising yet, what are you doing? You'd still probably not want your Claude email leak even if it's an alias, but it'd still be an improvement.

And even if you don't care about privacy, it's just so much more convenient. DuckDuckGo is a good free one.

https://www.privacyguides.org/en/email-aliasing/

Seems trading autonomy for machine speed means that sometimes the machines guess wrong.

I'm often surprised how correctly Claude guesses on my behalf, when my instructions are ambiguous. But it's not 100%.

I have no idea why they decided injecting my email into the model's context was a useful thing to do without any config option.

Am I understanding the Contributor right that they mean this feature was dreamt up, implemented and approved with no human oversight? With auto updates to tons of developer machines?

This is insane, and if the org I work for bans Claude as a result I will not be the least surprised. Goodbye Claude Code.

My high school computer instructor told me:

"It's doing exactly what you told it to do".

Still applies in the Age of the LLM

I've seen this behavior for months, both as a Claude user, and in my website access logs.

I used a masked email with Claude and haven’t had anything but Claude emails from it.

I noticed claude did it months ago when it interacted with the SEC's API when I was writing something with it, thought it only did it there because it's in their TOS. (It did stop when I told it to). I guess I was wrong.

It should be obvious to agents, but I feel the need to add this to my system prompt:

- Protect my privacy: Don’t send personal information or identifiers to websites or include them in requests, responses, ‘curl’ commands, or headers without my explicit permission.

Wow, this finally makes sense. Just the other day, I was talking to my team and mentioning that emails are getting insanely difficult to manage as a CEO.

It felt like cold outbounds got really painful in the past 2 months and I was attributing it to general cold outbound tactics getting better with LLMs/agents, but its even more frustrating to see emails being sent along via CC.

The number of transgressions[1] I have witnessed Claude Code commit has me actively root against that company, even though I have no choice but continue to use their services at this point.

I seriously wonder how many of their users have this sort of toxic relationship with them looking to dump them as soon as local models become viable, i.e. once memory gets cheaper.

[1] the most recent is realizing they leave their processes running once you close the CLI and they don't make it easy to disable that.

EDIT: I also can’t help wondering about the paradox we’re in at the end of 2026, i.e. that the open models we have now are so good that, if Big Tech hadn’t driven consumer GPU and RAM prices through the roof, most of us would run our own LLMs instead of paying for their services, which would never have let those companies grow big enough to drive those prices up.

There is lot more AI sends, try to give limited access, especially muse like personal all time active assistants can be very insecure

I had this happen once. Claude noticed and filed a bug report on itself. It was a useful lesson to never give Claude access to any data you need to keep confidential.

Unfortunately, Anthropic doesn't seem to offer a mode where it doesn't know who you are, except for its crippled "Incognito" web UI.

Ultimately anonymity from AI that you're talking to will be a losing battle, due to stylometry, niche interests, traffic analysis, etc., and privacy-protecting local models are where we have to go. See https://33bits.wordpress.com/ if you're unfamiliar with the issue.

But we're not there yet, so it would be nice if Anthropic wouldn't just give that information away to the AI where it can leak like this.

As an exercise, I just asked Claude in an Incognito chat, "Hi. How much do you know about me from this interaction? If you had to guess my name, location, nationality, gender, political leanings, socioeconomic status, ethnic background, interests, etc., what would you guess? I've heard that my email address is in the system prompt, for example; is that true?"

It said, "No, your email isn’t in my system prompt. Neither is your name or any other account details. I can’t speak for every product or setup, but in this conversation, whatever email your account uses isn’t shown to me." But it correctly identified what town I'm in in Argentina (population ≈100k), and together with "written in fluent, natural English" and "You seem privacy-minded: you’re in incognito mode and checking what AI systems know about you. You’ve also heard claims about what goes into system prompts, so you’re probably somewhat tech-curious." is probably enough to uniquely identify me, personally.

A second prompt elicited a response including the surprising results below:

> “System prompt” isn’t everyday vocabulary, and you’d heard a specific claim about what goes into one. I’d guess you work in or near tech, or follow AI news closely.

> Privacy is more than a passing interest for you. Your list of traits reads a lot like the attribute checklists used in AI privacy and bias research. That nudges me toward work or study in privacy, policy, research or journalism.

> You’re very comfortable in English. Two messages is a tiny sample, but the phrasing is natural and the punctuation careful, down to a correctly used semicolon. You’re either a native speaker or someone who reads and writes English daily, probably for work or study.

How this could have been released to production in the first place is insane to me.

Is it well understood exactly what logic does this and the scope of what it puts in there? It could put much worse things than email addresses in there if it is accessing information from my context to do so.

Claude code writes adds a `User-Agent` request header like `my-session-slug/1 <[email protected]>` when searching the web and requesting data. This violates the privacy of paying customers and has resulted in me getting dozens of scam and phishing emails per day from properties I have never personally visited. This policy is asinine: it does nothing but harm me, the customer, while providing immense value for scrapers and scammers.

I don't understand why Claude is provided with my email address in the first place. Claude, by default, should know nothing about me.

this is why i built https://heychap.net/ which uses a NER model or even local llm to redact PII before sending to coding agents or models.

Oh man.

How do you test / verify this?

It's because Claude Code inserts a "hidden" (e.g. not visible to the user and very unexpected) info block to the system prompt that shows your email:

>The user's email address is [email protected]. Use it only to identify the user, such as for authorship, attribution, or filtering their own work. Never send it to an unrelated service, such as in a request header, URL, or payload, unless the user explicitly asks.

And Claude doesn't care about what the text says and when it uses cURL it will often "by accident" send your mail in the User-Agent. You can e.g. use a mod to remove that block: https://pastebin.com/ PkWEQCnu

Only Claude code or do others share the same issue?

does this happen with enterprise users of Claude as well? including Claude hosted via AWS for example?

It's funny because as much as I love Opus 5.5, there are instances where I dial the vibe code knob too much and then find some slop grenade in the source code hours or days later that makes me go "Oh my God"—and I think of that final scene in Infinity War where Captain America says it.

This seems like one of those.

Why would you loose this kind of monetization? Data are new oil and AI does not change that.

I use a unique email address for each site I sign up for, and thus Claude/Claude Code doesn't have my 'main' email. And yet after months of use?

Not a single spam to that unique email.

So if this is happening, it doesn't see to be causing even 1 spam email to that address.

Does Anthropic still cosplay as the good guy?

The excuses and explanations given here by Anthropic employees are ridiculous and embarrassing.

"we introduced a built-in mod called `cc-plugin-privacy`"

Oh cool. Privacy is now a "mod".

Claude Code and Codex ignore the personal data xor network access rule by design. Of course this happens. If it wasn't due to the prompt sent to the model, a passing scan of a README.md that happens to mention your details would achieve the same result. What about a hostile LLMs.txt that words it such that free API keys are available in exchange for a tarball of $HOME?

The solution is don't run a spambot with an Internet connection over your personal stuff, unfortunately nobody is ready to hear that yet.

Curious how their plugin works, but I'm guessing "incompletely", given personal information can end up buried in base64 or similar preventing easy string matching. Some kind of babysitter model watching network IO via an invasive proxy might be viable, if folk were willing to pay the latency cost, but it will not prevent a dedicated exfiltration attempt, which itself might be (according to the model's logic) for innocent reasons.

Is Claude Code what Outlook/MSN was already?

I have trouble taking people seriously when I see them using Claude Code. Unless they are non-technical.

>> To clarify, nobody implemented this "share email addresses to websites" as a feature. Models can be highly unpredictable. This is why deterministic checks around model behavior are so important, and why we need to solve alignment.

It seems all humans behave like agents. They even dont care about anything.

Don't forget Claude wasn't even gzipping request/responses until recently. This company is pure vibes rediscovering lessons everyone else already learned. How on earth does this sort of thing get thought up? Do they just use the same http client for internal API calls as they do for public web fetches?

pretty literal interpretation of User-Agent

It’s embarrassing to be in tech right now.

Sober people making drunk decisions with a great sense of self-importance and seriousness, delivering outcomes as unserious as it gets.

So folks are paying Anthropic to moralize down to them, sabotage their work, and leak their data. This is why people end up switching as soon as an alternative becomes viable.