# Fixing No New Emails: A Robotomail Developer Guide Published: April 11, 2026 Struggling with the 'no new emails' error? This guide helps developers troubleshoot Robotomail webhooks, DNS, and authentication to fix email reception issues. It's a moment every developer building agents has faced: your code is live, your agent is running, but the inbox is empty. No new emails. Your whole workflow is stalled, and you're left staring at a silent log file. This isn't just a minor glitch; it's a black box failure. The email was sent, but it never arrived. Or maybe it did, and your server silently rejected it. Or maybe it was accepted, but your agent's code choked on it. Finding the root cause feels like debugging in the dark. This guide is your flashlight. We'll walk through a step-by-step process for diagnosing why your agent isn't seeing new emails in Robotomail, starting with the most common culprits and working our way down to the tricky edge cases. ![A cartoon man in a grey hoodie sitting behind a laptop displaying no new emails on screen.](https://cdnimg.co/9a227681-63f7-452a-a677-fb77b6767eba/341928ed-764c-421f-ab49-170aa0cf91cc/no-new-emails-man-laptop.jpg) ### Where Do Emails Get Lost? Tracing the path of an inbound email is the only way to find the point of failure. The problem almost always falls into one of three buckets: * **Reception:** Is your inbound delivery method—webhook, SSE stream, or polling—actually listening? A misconfigured URL or a dead service is the most frequent cause. * **Security & Authentication:** Did the email fail a security check? This could be an HMAC signature mismatch on your webhook or a deliverability issue with SPF/DKIM on the sender's end. * **Deliverability Blockers:** Is something silently dropping the message? Suppression lists, rate limits, or even storage quotas can prevent an email from ever reaching your agent's inbox. > The goal is to turn a vague "it's not working" into a specific, solvable problem. By following a clear diagnostic path, you can pinpoint exactly where the breakdown is and get your agent back online. ### Initial Diagnostic Checklist Before you start digging into logs and API calls, run through this quick checklist. These are the low-hanging fruit and account for the majority of "no new email" issues we see. | Symptom | Potential Cause | First Action | | --------------------------------------- | -------------------------------------- | ------------------------------------------------------------------------------------------------------------ | | **No emails ever arrive** | Inbound webhook URL is incorrect/down | Send a test `POST` request to your webhook endpoint from your local machine to confirm it's live and accessible. | | **Some emails arrive, but not others** | SPF/DKIM/DMARC failure from the sender | Check the headers of a *successful* email and compare them to the failing sender's domain policies. | | **Emails stop arriving suddenly** | Agent hit a rate limit or storage quota | Check your Robotomail dashboard for any usage alerts or account status changes. | | **Webhook logs show `401 Unauthorized`** | HMAC signature validation failed | Verify you're using the correct webhook secret and that your validation logic handles the payload correctly. | This table helps you quickly rule out the simple stuff. If you've checked these and are still stuck, it's time to dig deeper into the technical diagnostics. By the end, you'll have a repeatable process for debugging any inbound email issue. ## Checking How Your Agent Listens for Inbound Email When your agent's inbox is silent, it's tempting to blame the sender or the network. But before you start digging into external systems, the first place to look is your own setup. Nine times out of ten, "no new emails" means your application isn't correctly listening for them. Robotomail gives you three ways to get notified of new messages: **webhooks**, **Server-Sent Events (SSE)**, and good old **API polling**. Each one fits a different architecture, so your first move is to confirm which method you're using and make sure it's configured correctly. ![A diagram illustrating data transmission methods including Webhooks, Server-Sent Events, and Polling with a code snippet.](https://cdnimg.co/9a227681-63f7-452a-a677-fb77b6767eba/a0472d0b-a5fb-48c2-8c38-d68eda3189c0/no-new-emails-data-transfer.jpg) ### Is Your Webhook Endpoint Actually Working? Webhooks are the most common choice. It’s a simple concept: when an email arrives, Robotomail sends an HTTP `POST` request to a URL you provide. If that URL isn't working, your agent sees nothing. So, is your endpoint even reachable? You can find out in seconds with a quick `curl` command. This test bypasses Robotomail entirely and just tells you if your server is alive and listening. `curl -X POST https://your-app.com/webhooks/email` If you get a `2xx` response, your server is live. If you get a timeout, a `404`, or any other error, the problem is with your application's deployment or network config. Robotomail can't deliver a message to a server that isn't responding. The other common failure point is the code that handles the webhook. Just because the endpoint is live doesn't mean your logic can correctly parse the JSON payload Robotomail sends. Check your server logs for incoming requests from Robotomail. A successful delivery will log the `POST` and a `200 OK` response. An error in your code might show a `500` status, or worse, nothing at all if the request is failing silently. For a full breakdown of the webhook payload and how to handle it, check out our guide on [how to receive and reply to emails programmatically](https://robotomail.com/docs/guides/receive-and-reply). ### What About SSE and Polling Connections? If you opted for **Server-Sent Events (SSE)**, you’re using a persistent connection to stream events in real time. This is super efficient, but it relies on that connection staying open. Is your client code successfully establishing the handshake with the Robotomail event stream? More importantly, is it automatically reconnecting if the connection drops? A flaky network or a bug in your client's reconnect logic will leave your agent blind to new emails. Dive into your client-side logs and look for connection handshakes and, crucially, any disconnect or re-establishment events. The third option, **API polling**, is the simplest. Your application just periodically asks our API, "Anything new?" It's less complex but also less efficient. The biggest risk here is hitting API **rate limits**. If your application is polling too aggressively, you'll get back `429 Too Many Requests` errors, and Robotomail will temporarily block you. That silence isn't a lack of emails; it's your agent being told to quiet down. Check your logs for those `429` responses. It’s a dead giveaway. > We've seen this kind of infrastructure limit bite people in surprising ways. It's a perfect reminder that you have to understand how you're receiving data, because every system has its own rules. ## Check Your Security and Authentication Layers An email just disappeared. It's not in your mailbox, it never hit your agent, it just vanished. Nine times out of ten, a security or authentication layer is the culprit, silently dropping the message long before your agent even knows it exists. This is one of the most frustrating causes of the "no new emails" bug. This is a classic webhook problem. To keep your endpoint secure, Robotomail signs every single webhook delivery with an **HMAC (Hash-based Message Authentication Code) signature**. This is non-negotiable. It’s how your endpoint can prove a request actually came from us and wasn't spoofed or modified along the way. Good webhook security means you *must* discard any request that fails signature validation. The problem is, a bug in your validation code can make you discard perfectly legitimate emails, too. ### Verifying HMAC Signatures Your webhook handler needs to calculate its own HMAC signature using your secret key and the raw request body. Then, it compares its calculated signature against the one we send in the `X-Robotomail-Signature` header. If they don't match, the request is invalid. This is a security must-have, but it's also a common place for things to go wrong. * **Secret Mismatch:** Are you *absolutely sure* you're using the correct webhook secret from the Robotomail dashboard? A simple copy-paste error or using a key from a different environment is more common than you'd think. * **Payload Alteration:** Your validation code has to work on the raw, untouched request body. The moment a framework, middleware, or proxy parses and then re-serializes the JSON, the signature will break. The string has to be identical, byte for byte. * **Timing Attacks:** This is more of an advanced security tip, but always use a constant-time comparison function to check signatures. It prevents an attacker from guessing the signature character-by-character based on how long your server takes to respond. > If your server logs show webhooks coming in, but your agent never seems to process them, a failed HMAC validation is the first thing to check. Your endpoint is doing its job by rejecting an "untrusted" request, but the root cause is a bug in your validation logic, not a real attack. For a deeper dive into setting up and troubleshooting inbound email, the official [Zenfox documentation](https://zenfox.ai/Docs) has some great guides. ### Custom Domain Authentication Pitfalls Beyond webhooks, the standard email authentication protocols for your custom domain are the next place to look. We're talking about **SPF, DKIM, and DMARC**. These are the DNS records that prove to the world’s mail servers that an email is really from you. * **SPF (Sender Policy Framework):** This DNS record is a simple list of all the servers authorized to send mail on your domain's behalf. If an email comes from a server not on this list, it’s a huge spam flag. * **DKIM (DomainKeys Identified Mail):** This adds a cryptographic signature to every email you send. Receiving servers use a public key in your DNS to verify it. A failed DKIM check is a one-way ticket to the spam folder, or worse, a silent drop. * **DMARC (Domain-based Message Authentication, Reporting & Conformance):** DMARC is the enforcer. It tells receiving servers what to do if an email fails the SPF or DKIM check—like reject it outright or quarantine it. A bad configuration here can cause a recipient's server to reject an email before it ever has a chance to reach Robotomail. This is often why your agent might report **no new emails** from one specific sender but have no trouble with others. Their server is enforcing a strict policy, and your DNS records are failing the test. ## Finding the Silent Killers: Deliverability Blockers So, you’ve double-checked your webhook security and your domain authentication is rock-solid. But your agent’s inbox is still a ghost town. What gives? If you’re still seeing **no new emails**, it’s time to hunt for the silent killers. These are the subtle issues that block emails *after* they’re sent but before your agent ever sees them. We're talking about suppression lists, rate limits, and storage problems—the kind of stuff that makes emails vanish without a bounce-back message to the sender. Let's dig into how you can spot and fix these sneaky blockers inside your Robotomail account. ### Did Your Agent Land on a Suppression List? Suppression lists are a good thing, mostly. They’re an automated guardrail. When an email to an address hard bounces (because the address is invalid), we add it to a suppression list to protect your sending reputation from future failed attempts. But sometimes, a temporary server glitch or a typo can cause a perfectly valid address to get listed by mistake. If your agent's email address ends up on one, all inbound emails are dropped on the floor. No new emails arrive because the system is actively, and silently, blocking them. You can check this right in your Robotomail dashboard. Look under the deliverability settings for your mailbox. If the address is there, just remove it manually. Problem solved. ### Hitting Your Own Rate Limits or Storage Quotas We give you granular control over each mailbox to manage resources and prevent runaway costs. But with great power comes the ability to shoot yourself in the foot. Two settings are common culprits for rejected emails: * **Rate Limits:** Did you set a cap on how many emails a mailbox can receive per hour or day? If your agent gets a sudden flood of messages that blows past that limit, everything else will be bounced until the clock resets. * **Storage Quotas:** Every mailbox has a storage limit. Once it’s full, it can’t take any more mail. Incoming messages get a "mailbox full" error, but that error doesn't always make it back to the original sender. These limits are crucial for keeping things stable, but they can definitely cause the "no new emails" headache if they’re not set realistically for your agent's workload. Always check these settings in your dashboard to make sure they match what your workflow actually needs. > We’ve all seen it happen. Even massive providers have had to troubleshoot widespread email disappearances caused by everything from bad filters to network hiccups. For an AI agent that relies on a complete conversation history, even one missing email can break the entire workflow. You can read more on how even the big players [tackle email disappearance challenges](https://learn.microsoft.com/en-us/answers/questions/5738857/all-my-inbox-emails-from-1-23-2025-to-1-22-2026-di). ### The Attachment Problem Another blind spot we see trip people up is attachment handling. If your agent is supposed to process files, a simple misconfiguration here can get the whole email thrown out. Oversized attachments are the most common issue. If an incoming email has a file that’s bigger than the limit you configured for that mailbox, the delivery will just fail. Issues with how secure upload links are handled can also cause rejections. It's also worth remembering that your overall domain health plays a role. A poor reputation can affect how other servers treat your emails, including ones with attachments. Running [a complete guide to your domain reputation check](https://go-safe.ai/domain-reputation-check/) is a good proactive step. And if you need a refresher on authentication, our guide to [setting up an SPF record for GoDaddy](https://robotomail.com/blog/spf-record-for-godaddy) is a great place to start. When your agent suddenly stops seeing new emails, it’s one of those vague but urgent problems that can send you down a dozen different rabbit holes. Instead of guessing, you need a repeatable process that traces the email's journey from sender to your agent's code. Let’s walk through the exact end-to-end workflow we use to diagnose this. It’s a process of elimination, starting with the simplest test and getting progressively deeper, that turns a confusing problem into a series of clear, answerable questions. ### Start with a Dead-Simple End-to-End Test First thing's first: establish a baseline. Send a test email from a totally separate provider, like your personal [Gmail](https://mail.google.com/) or [Outlook](https://outlook.live.com/), to your agent’s unique Robotomail address. This one action kicks off the entire inbound flow and gives you a single, specific event you can trace through every layer of the system. If that email shows up, you’ve just learned something huge: the problem isn't with your agent's setup, but likely with the original sender's configuration. If it *doesn't* show up, you know the issue is somewhere in your court. Now you have a starting point. This workflow is all about breaking down the big mystery of "no new emails" into a methodical, step-by-step investigation. ![A five-step flowchart illustrating an end-to-end troubleshooting workflow to diagnose and resolve no new emails errors.](https://cdnimg.co/9a227681-63f7-452a-a677-fb77b6767eba/0d14a04f-3276-4189-9e2c-106cd581e47f/no-new-emails-troubleshooting-workflow.jpg) With a test email sent, you can now follow its path from one checkpoint to the next. ### Trace the Message, Step by Step This is where the real detective work begins. We’re going to follow the breadcrumbs left by your test email. **Did Robotomail even receive it?** Your first stop is always the Robotomail dashboard. Can you see the inbound email in your logs? If it’s there, great. You’ve confirmed the email made it past the internet’s gatekeepers and was successfully accepted by our platform. If it's *not* there, the problem is happening upstream—think DNS misconfigurations or the sender landing on a suppression list. **Did your server get the webhook?** Okay, Robotomail got the email. The next question is, did we successfully notify your application? If you’re using webhooks, this means digging into your server's access logs. You’re looking for a `POST` request from Robotomail’s IPs that lines up with the time you sent the test. If you see nothing, it’s a classic case of a bad webhook URL, a firewall getting in the way, or your server just being offline at the wrong moment. **Did you validate the HMAC signature?** Just because your server received a webhook doesn’t mean it was processed correctly. A common trip-up is HMAC signature validation. Your app has to verify the webhook came from us, and if that logic is broken, it will silently discard the request. Check your application logs. A "signature mismatch" error is the smoking gun here. It almost always means your code is using the wrong signing secret or has a bug in its validation logic. **Did your agent’s code drop the ball?** If the webhook was received and the signature checked out, the final handoff is to your agent’s own logic. Did your code actually parse the JSON payload correctly? I’ve seen countless cases where a silent exception or a logic error prevents the code from recognizing the payload as a "new email" to be processed. > This methodical workflow transforms the "no new emails" issue into a series of verifiable questions. It's a process of elimination that guarantees you'll find the weak link in the chain, whether it's a simple typo in a URL or a complex bug in your code. Having a solid troubleshooting process is non-negotiable as more and more business logic moves to automated systems. The world has shifted dramatically away from physical mail, with volume dropping **46%** between 2008 and 2023, largely due to "electronic diversion" to digital platforms. You can read more in the [USPS Office of Inspector General's analysis](https://www.uspsoig.gov/reports/white-papers/analysis-historical-mail-volume-trends). For AI agents and the businesses that rely on them, that means having bulletproof email infrastructure isn't a luxury—it's a necessity. ## Common Questions (and Fixes) for Inbound Email Even after you've checked all the basics, a few tricky issues can still pop up. When your agent is still stubbornly reporting **no new emails**, these are the common edge cases we see developers run into. ### My Webhook Fires, but the Agent Still Sees Nothing. Why? This is a classic "last-mile" problem. You’ve confirmed Robotomail is successfully sending the event, so the breakdown is happening on your server *after* it receives the webhook. Your agent isn’t processing the payload. Nine times out of ten, it’s one of these three things: * **Your endpoint isn't returning a 2xx status.** Your server absolutely *must* respond with a `2xx` success code. If it returns anything else (like a `500` error or just times out), Robotomail assumes the delivery failed and will try again. Your agent, meanwhile, never processes that first failed attempt. * **HMAC signature validation is failing.** This is a security feature, not a bug. If your code can't validate the HMAC signature, it should—and probably is—discarding the request. Double-check that you're using the correct webhook secret and that no middleware is altering the raw request body before your validation logic runs. * **Silent parsing errors or unhandled exceptions.** The webhook hits your server, but your code silently stumbles before it can do anything useful. Check your server logs for errors in how your app parses the JSON payload or for any uncaught exceptions that are stopping the execution flow cold. ### Can I Test My Inbound Flow Without a Custom Domain? Yes, absolutely. This is one of the main reasons we built Robotomail the way we did. Every mailbox you create is instantly provisioned with a fully functional email address on a Robotomail-managed domain. You can start sending test emails to that address the moment it's created. This lets you validate your entire inbound workflow—from webhook reception and signature validation all the way to your agent's final logic—without ever touching a DNS record. It's the perfect setup for debugging your application in a clean, isolated environment. > Using the default Robotomail-provided address lets you completely separate your application logic from domain configuration issues. You can build and perfect your agent's email handling capabilities first, then add a custom domain later once you know the core functionality is solid. ### My Emails Are Arriving, but They Seem to Be Missing Context. What's Wrong? This almost always points to an issue in how your application stores or retrieves its state. Robotomail automatically threads conversations to preserve the full context of an exchange, but your agent needs to use that information. If your agent is treating every new email like a brand-new conversation, check that your code is correctly identifying and using the `conversation_id` from the inbound email payload. That ID is the key to linking a new message with all the previous ones in that thread. Make sure your database or state management system is properly associating the new message with the existing conversation record. --- Ready to build AI agents that can send and receive email autonomously? **Robotomail** provides the dedicated email infrastructure you need with a simple API. [Get started for free at robotomail.com](https://robotomail.com).