Verify Email Addresses with Go

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"time"
)

const (
	apiURL = "https://api.validemail.net/"
	apiKey = "YOUR_API_KEY" // find it in your ValidEmail dashboard
)

type AdditionalInfo struct {
	Key   string `json:"Key"`
	Value string `json:"Value"`
}

type VerificationResult struct {
	IsValid             bool             `json:"IsValid"`
	Score               int              `json:"Score"`
	Email               string           `json:"Email"`
	State               string           `json:"State"`
	Reason              string           `json:"Reason"`
	Domain              string           `json:"Domain"`
	Free                bool             `json:"Free"`
	Role                bool             `json:"Role"`
	Disposable          bool             `json:"Disposable"`
	AcceptAll           bool             `json:"AcceptAll"`
	Tag                 bool             `json:"Tag"`
	MXRecord            string           `json:"MXRecord"`
	RetryAfterSeconds   *int             `json:"RetryAfterSeconds"`
	EmailAdditionalInfo []AdditionalInfo `json:"EmailAdditionalInfo"`
}

var client = &http.Client{Timeout: 90 * time.Second}

func verifyEmail(email string, maxRetries int) (*VerificationResult, error) {
	var result VerificationResult

	for attempt := 0; attempt < maxRetries; attempt++ {
		query := url.Values{"email": {email}, "token": {apiKey}}
		resp, err := client.Get(apiURL + "?" + query.Encode())
		if err != nil {
			return nil, err
		}

		body, err := io.ReadAll(resp.Body)
		resp.Body.Close()
		if err != nil {
			return nil, err
		}

		if resp.StatusCode != http.StatusOK {
			return nil, fmt.Errorf("request failed with HTTP %d: %s", resp.StatusCode, body)
		}

		if err := json.Unmarshal(body, &result); err != nil {
			return nil, err
		}

		// "Unknown" means the verification is still in progress (e.g. greylisting).
		if result.State == "Unknown" && result.RetryAfterSeconds != nil {
			time.Sleep(time.Duration(*result.RetryAfterSeconds) * time.Second)
			continue
		}

		return &result, nil
	}

	return &result, nil // still pending after maxRetries — treat as risky
}

func main() {
	result, err := verifyEmail("someone@example.com", 3)
	if err != nil {
		panic(err)
	}

	fmt.Println("Valid: ", result.IsValid)
	fmt.Println("Score: ", result.Score)
	fmt.Println("State: ", result.State)
	fmt.Println("Reason:", result.Reason)

	if result.IsValid && result.Score >= 80 {
		fmt.Println("Safe to send.")
	}
}