GMX Mail to Webhook

Why Route GMX Mail Emails to a Webhook?

GMX Mail is a free email service operated by United Internet, widely used in Germany and across Europe as well as North America. While GMX Mail is a capable email platform, its native tooling for programmatic automation was not built for developers who need structured, reliable data delivery to backend systems.

The native approach — GMX IMAP polling — introduces significant operational overhead. You need to manage credentials, poll or maintain persistent connections, and write custom parsing logic for every message field you care about. When your team is moving fast, that friction adds up to hours of maintenance per integration.

JsonHook eliminates that overhead by accepting inbound mail on your behalf and immediately firing a structured JSON payload to any HTTPS endpoint you specify. The email is parsed, attachments are base64-encoded, and headers are normalised — so your webhook handler can focus entirely on business logic rather than MIME parsing.

Below are the core benefits of routing your GMX Mail messages through JsonHook instead of relying on the native alternative:

• Limitation avoided: GMX does not provide a public API for accessing or automating email; IMAP is the only available programmatic access method.
• Limitation avoided: GMX's IMAP server occasionally applies aggressive rate limiting that can cause polling-based integrations to miss messages during high-volume periods.
• Limitation avoided: GMX's free tier does not support conditional or filter-based forwarding — all mail is forwarded or none is.
• Zero-polling architecture: JsonHook pushes to your endpoint the moment mail arrives — no long-running background jobs needed.
• Automatic attachment handling: PDFs, images, and other file types are extracted, base64-encoded, and included in the JSON payload with their original MIME type.
• Retry with exponential back-off: If your endpoint is temporarily unavailable, JsonHook retries automatically — something the GMX IMAP polling does not do natively.
• Webhook signatures for security: Every delivery includes an HMAC-SHA256 signature header so you can verify the payload originated from JsonHook.

Whether you are building a support-ticket ingestion pipeline, a lead-capture workflow, or an automated document processor, JsonHook gives you a consistent, typed interface to GMX Mail messages without the fragility of raw SMTP or polling-based API integrations.

How to Forward GMX Mail to JsonHook

Getting GMX Mail emails delivered to your webhook takes about five minutes. The process has two parts: creating a JsonHook address via the API, and configuring GMX Mail to forward a copy of each incoming message to that address.

1. Log in to GMX and click the gear/settings icon at the top right, then select E-mail Settings.
2. Navigate to Auto-reply and forward › Forward e-mails.
3. Enable forwarding, enter your JsonHook inbound address in the forwarding field, and choose whether to keep a copy in your GMX inbox.
4. Click Save. GMX activates forwarding immediately; no address verification step is required.

Once forwarding is active, every email that arrives in your GMX Mail inbox (or matches your filter) will be relayed to your JsonHook address, parsed, and delivered to your endpoint as a JSON payload within seconds.

You can create your JsonHook inbound address with a single curl command. Replace YOUR_API_KEY with the key from your dashboard and set webhookUrl to your endpoint:

curl -X POST https://jsonhook.com/api/addresses \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "label": "GMX Mail inbound",
    "webhookUrl": "https://your-app.example.com/webhooks/email",
    "secret": "a-random-signing-secret"
  }'

The response includes your unique @in.jsonhook.com address. Copy that address and paste it into the forwarding field in your GMX Mail settings. That is all the infrastructure you need to stand up.

GMX Mail vs GMX IMAP polling

When developers first explore email-to-webhook automation they typically discover GMX IMAP polling — the official programmatic route provided by GMX (United Internet). The table below shows how it compares to using JsonHook as an intermediary.

The native approach through GMX IMAP polling requires you to set up OAuth credentials or API keys, maintain a long-running listener or polling job, write your own MIME parser, and implement your own retry queue. Any one of those steps can become a reliability bottleneck in production.

JsonHook handles all of that infrastructure on your behalf. You get a single HTTPS webhook call with a predictable JSON schema every time a GMX Mail email arrives — no polling, no credential rotation, no MIME parsing, and no bespoke retry code to maintain.

JSON Payload Example

When a GMX Mail email is forwarded to your JsonHook address and delivered to your endpoint, the request body looks like the following. All fields are consistently present; optional fields such as htmlBody and attachments are included when the source message contains them.

{
  "id": "msg_01j8xkr4p2vn3q7w",
  "receivedAt": "2026-03-15T14:32:07.412Z",
  "from": {
    "name": "Alice Smith",
    "address": "[email protected]"
  },
  "to": [
    {
      "name": "",
      "address": "[email protected]"
    }
  ],
  "subject": "Your GMX Mail message subject here",
  "textBody": "Plain-text content of the email body.",
  "htmlBody": "<div>HTML version of the email body.</div>",
  "headers": {
    "message-id": "<[email protected]>",
    "x-mailer": "GMX (United Internet)",
    "mime-version": "1.0"
  },
  "attachments": [
    {
      "filename": "document.pdf",
      "contentType": "application/pdf",
      "size": 84234,
      "content": "JVBERi0xLjQK..."
    }
  ],
  "spf": "pass",
  "dkim": "pass"
}

The id field is a unique, stable identifier you can use for idempotent processing. The spf and dkim fields reflect the authentication results JsonHook observed when receiving the message, which you can use to enforce additional trust policies in your handler.

Attachment content is standard base64. Decode it with a single call in any language — Buffer.from(att.content, 'base64') in Node.js, base64.b64decode(att.content) in Python, and so on.

Go handler for GMX Mail messages forwarded through JsonHook:

package main

import (
  "crypto/hmac"
  "crypto/sha256"
  "encoding/hex"
  "encoding/json"
  "fmt"
  "io"
  "net/http"
  "os"
)

type EmailPayload struct {
  From    struct{ Address string } `json:"from"`
  Subject string                   `json:"subject"`
  TextBody string                  `json:"textBody"`
}

func webhook(w http.ResponseWriter, r *http.Request) {
  body, _ := io.ReadAll(r.Body)
  mac := hmac.New(sha256.New, []byte(os.Getenv("JSONHOOK_SECRET")))
  mac.Write(body)
  if hex.EncodeToString(mac.Sum(nil)) != r.Header.Get("X-JsonHook-Signature") {
    http.Error(w, "unauthorized", 401); return
  }
  var msg EmailPayload
  json.Unmarshal(body, &msg)
  fmt.Printf("GMX: %s → %s
", msg.From.Address, msg.Subject)
  w.WriteHeader(200)
}

func main() {
  http.HandleFunc("/webhooks/email", webhook)
  http.ListenAndServe(":8080", nil)
}

Common GMX Mail to Webhook Use Cases

GMX is a major email provider across Europe and North America, particularly popular in Germany and with users who prefer ad-supported free accounts with generous storage. GMX's forwarding capability makes it straightforward to bridge GMX inboxes into automated webhook workflows via JsonHook.

• European market communications: Applications serving European customers often receive messages from GMX addresses. Route those into a webhook to track regional engagement and apply GDPR-compliant data handling automatically.
• Classified ad reply automation: GMX is commonly used to respond to classified ad listings. Forward reply emails from GMX to a webhook that notifies sellers and logs inquiry details in a CRM.
• Newsletter subscription management: GMX users who subscribe via email can have their subscription confirmation messages routed through a webhook that triggers list additions and welcome sequences automatically.
• Utility alert forwarding: Users who receive utility bills, bank statements, and official notifications at their GMX address can forward those to a webhook for automated document archival and categorisation.