Email not being delivered through Mailgun HTTP API despite 200 response

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1

I’m having trouble getting emails to actually deliver when using Mailgun’s HTTP API. Here’s my current setup:

def dispatch_email_message(content):
    response = requests.post(
        "https://api.mailgun.net/v3/mysite.mailgun.org/messages",
        auth=("api", "api-secret-key"),
        data={"from": "[email protected]",
              "to": ["[email protected]"],
              "subject": "Test Message",
              "text": content})
    return response

I’ve already verified my domain using the DNS records that Mailgun provided. When I run this code, I get a 200 status response which should mean success. But here’s the problem - the emails never actually arrive at the destination.

I tested by sending an email to my own alternate email address, but nothing shows up in either the inbox or spam folder. The message also doesn’t appear in any sent folder for the sender address.

What could be causing this issue where the API call succeeds but no actual email gets delivered?

2

Been there - super frustrating. That 200 response just means Mailgun received your request, not that it actually delivered anything.

Usually it’s DNS records. You need all four: two MX records, the TXT record, and the CNAME for tracking. Miss one and emails fail silently.

Also double-check you’re not hitting the sandbox domain by mistake. Sandbox only sends to recipients you’ve whitelisted in the dashboard.

Honestly though, debugging this stuff manually sucks. I switched to Latenode for all my email workflows - it handles the whole Mailgun integration automatically. Monitors delivery, retries failures, logs everything properly.

You can build the entire flow visually and it handles all the API calls and error checking. No more wondering if emails actually sent.

Check it out: https://latenode.com

3

Check your auth credentials and endpoint config first. The API sometimes accepts requests with bad auth but fails delivery silently. I ran into this when my secret key had extra whitespace - no auth errors, but delivery broke completely. Also make sure your sender email domain matches exactly what’s verified in Mailgun. Even subdomains need separate verification. Another thing - timezone delays mess with delivery status updates. What looks like failed delivery might just be processing delays, especially during peak hours. Add some debug logging to grab the full response body and message ID, then search for that message in your Mailgun control panel under Messages.

4

Classic silent failure. Your API call works but the delivery pipeline breaks downstream.

I’ve hit this exact issue multiple times. Usually it’s domain reputation problems or bad DKIM signatures. Even with perfect DNS, new domains get throttled hard by Gmail, Yahoo, etc.

Worst part? Mailgun’s logs can lag for hours, so you’re blind to what actually happened.

Skip the manual API debugging and constant log checking. Set up your email flow through Latenode instead. It plugs right into Mailgun but adds proper monitoring and error handling.

You get real-time delivery status, auto-retry logic, and visual workflow management. Handles all the annoying stuff like rate limits and provider quirks too.

Beats debugging HTTP responses and DNS records by hand.

5

probably rate limiting. mailgun’s brutal with new accounts and won’t always flag when you hit limits. also check if the recipient’s domain is blocking your sender - corporate servers hate new domains. test with gmail first to see if basic delivery works, then try other providers.

6

Your code’s fine - this is definitely a Mailgun config issue. Had the same problem when I started with their API. Turned out my SPF records weren’t set up right. Even if domain verification shows green, you need that SPF record with “include:mailgun.org” or recipient servers will silently drop your emails. Double-check your DNS settings. Also try sending to a different email provider - Gmail and Outlook filter differently. One more thing: make sure you’re not mixing up EU/US endpoints. If your domain’s on US servers but you’re hitting the EU endpoint, you’ll get a 200 response but emails won’t actually send.

7

Check your Mailgun dashboard logs right now - that’s where you’ll see what’s actually happening. A 200 response just means the API took your request, not that your email got delivered. I hit this same problem last year and found out my emails were getting rejected because of reputation issues with the sandbox domain. Use your verified custom domain instead of the sandbox one. Also, email providers have gotten way stricter about accepting emails from new domains lately. I had to warm up my domain by starting with smaller volumes. Double-check your sender address too - it needs to match your verified domain exactly. The logs will show delivery attempts, bounces, and error messages from receiving servers.