SMTP
503 Bad Sequence Antwort simulieren
The commands were sent in the wrong order. SMTP requires a specific command sequence (EHLO, MAIL FROM, RCPT TO, DATA) and this error indicates a step was skipped or repeated.
Vollständige Referenz anzeigen →1 HTTP-Antwort
HTTP/1.1 503 Bad Sequence
Content-Type: application/json
Date: Tue, 25 Feb 2026 12:00:00 GMT
Retry-After: 300
Content-Length: 52
{
"error": "service_unavailable",
"retry_after": 300
}
2 Mit curl testen
curl -i https://httpbin.org/status/503
3 503 Bad Sequence in Ihrem Framework zurückgeben
django
from django.http import JsonResponse
def my_view(request):
return JsonResponse(
{"error": "service_unavailable", "retry_after": 300},
status=503,
)
flask
from flask import Flask, jsonify
app = Flask(__name__)
@app.route("/endpoint")
def my_endpoint():
return jsonify({"error": "service_unavailable", "retry_after": 300}), 503
fastapi
from fastapi import FastAPI
from fastapi.responses import JSONResponse
app = FastAPI()
@app.get("/endpoint")
def my_endpoint():
return JSONResponse(
content={"error": "service_unavailable", "retry_after": 300},
status_code=503,
)
express.js
// Express.js
app.get('/endpoint', (req, res) => {
res.status(503).json({"error": "service_unavailable", "retry_after": 300});
});
spring boot
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import java.util.Map;
@RestController
public class MyController {
@GetMapping("/endpoint")
public ResponseEntity<Map<String, Object>> myEndpoint() {
return ResponseEntity
.status(503)
.body(Map.of("error", "bad_sequence",
"message", "Bad Sequence"));
}
}
go net/http
package main
import (
"encoding/json"
"net/http"
)
func myHandler(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(503)
json.NewEncoder(w).Encode(map[string]string{
"error": "bad_sequence",
"message": "Bad Sequence",
})
}
ruby on rails
class MyController < ApplicationController
def my_action
render json: {"error": "service_unavailable", "retry_after": 300},
status: :bad_sequence
end
end
asp.net core
// ASP.NET Core Minimal API
app.MapGet("/endpoint", () =>
Results.Json(
new { error = "bad_sequence", message = "Bad Sequence" },
statusCode: 503
)
);