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📨 Build an Email Validation Tool with Python & Tkinter (Step-by-Step)

#tutorial #python #tkinter #emailvalidationtool

In this tutorial, we’ll build a desktop Email Validation Tool using Python + Tkinter.

By the end, your app will:

Validate email format using regex

Check if the domain has MX records (can receive email)

Keep a history of validated emails

Export results to a .txt file

Support light/dark mode

Stay responsive using threading

No advanced GUI knowledge required — we’ll go step by step.

📦 Step 1: Import Required Libraries

Let’s start by importing everything we need.

import sys
import os
import re
import threading
import tkinter as tk
from tkinter import ttk, messagebox, filedialog
import dns.resolver
import sv_ttk
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What these are for:

tkinter / ttk → GUI components

re → email format validation

threading → prevent UI freezing

dns.resolver → MX record lookup

sv_ttk → modern Tkinter theme

📌 Install missing packages:

pip install dnspython sv-ttk

🛠 Step 2: Helper Functions
Resolve file paths (useful for packaging later)

def resource_path(file_name):
    base_path = getattr(sys, "_MEIPASS", os.path.dirname(os.path.abspath(__file__)))
    return os.path.join(base_path, file_name)
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Status bar updates

def set_status(msg):
    status_var.set(msg)
    root.update_idletasks()
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This keeps users informed while background tasks run.

🖥 Step 3: Create the Main Application Window

root = tk.Tk()
root.title("Email Validation Tool")
root.geometry("720x680")
sv_ttk.set_theme("light")
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Creates the main window

Sets size and title

Applies a modern light theme

🌍 Step 4: Global State Variables

dark_mode_var = tk.BooleanVar(value=False)
email_var = tk.StringVar()
validation_result_var = tk.StringVar(value="Result: —")
email_history = []
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These variables help us:

Track dark mode

Read email input

Display validation results

Store history

🌗 Step 5: Dark Mode Toggle

def toggle_theme():
    bg = "#2E2E2E" if dark_mode_var.get() else "#FFFFFF"
    fg = "white" if dark_mode_var.get() else "black"

    root.configure(bg=bg)

    for w in ["TFrame", "TLabel", "TLabelframe",
              "TLabelframe.Label", "TCheckbutton"]:
        style.configure(w, background=bg, foreground=fg)

    email_entry.configure(background=bg, foreground=fg)
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This manually updates widget colors when dark mode is toggled.

📧 Step 6: Email Validation Logic
6.1 Check Email Format (Regex)

def is_valid_email_format(email):
    regex = r"^[\w\.-]+@[\w\.-]+\.\w+$"
    return re.match(regex, email) is not None
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This ensures the email looks valid.

6.2 Check Domain MX Records

def has_mx_record(domain):
    try:
        records = dns.resolver.resolve(domain, 'MX')
        return bool(records)
    except Exception:
        return False
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MX records indicate whether a domain can receive email.

6.3 Start Validation (UI Thread)

def validate_email():
    email = email_var.get().strip()

    if not email:
        messagebox.showwarning("Error", "Please enter an email address.")
        return

    set_status("Validating email...")
    threading.Thread(
        target=_validate_email_thread,
        args=(email,),
        daemon=True
    ).start()
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We run validation in a background thread so the UI doesn’t freeze.

6.4 Validation Worker Thread

def _validate_email_thread(email):
    if not is_valid_email_format(email):
        validation_result_var.set("Result: ❌ Invalid format")
        set_status("Validation complete")
        return

    domain = email.split("@")[1]

    if has_mx_record(domain):
        validation_result_var.set("Result: ✅ Valid email")
    else:
        validation_result_var.set("Result: ⚠ Domain may not receive emails")

    add_to_history(email)
    set_status("Validation complete")
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🗂 Step 7: Email History Management
Add to history list

def add_to_history(email):
    email_history.append(email)
    history_list.insert(tk.END, f"{len(email_history)} • {email}")
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Export History to .txt

def export_history_txt():
    if not email_history:
        messagebox.showinfo("Empty History", "No emails to export.")
        return

    file_path = filedialog.asksaveasfilename(
        defaultextension=".txt",
        filetypes=[("Text Files", "*.txt")],
        title="Export Email History"
    )

    if not file_path:
        return

    try:
        with open(file_path, "w", encoding="utf-8") as f:
            f.write("Email Validation History\n")
            f.write("=" * 30 + "\n\n")
            for i, email in enumerate(email_history, 1):
                f.write(f"{i}. {email}\n")

        set_status("Email history exported")
        messagebox.showinfo("Export Successful", "Email history saved successfully.")
    except Exception as e:
        messagebox.showerror("Export Failed", str(e))
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🎨 Step 8: Styling

style = ttk.Style()
style.theme_use("clam")
style.configure("Action.TButton",
                font=("Segoe UI", 11, "bold"),
                padding=8)
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Creates bold action buttons.

📊 Step 9: Status Bar

status_var = tk.StringVar(value="Ready")

ttk.Label(
    root,
    textvariable=status_var,
    anchor="w"
).pack(side=tk.BOTTOM, fill="x")
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🧱 Step 10: Build the UI Layout
Main Container

main = ttk.Frame(root, padding=20)
main.pack(expand=True, fill="both")
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Title & Input

ttk.Label(
    main,
    text="Email Validation Tool",
    font=("Segoe UI", 22, "bold")
).pack()

email_entry = ttk.Entry(
    main,
    textvariable=email_var,
    font=("Segoe UI", 14),
    justify="center"
)
email_entry.pack(fill="x", pady=8)

Result Display
ttk.Label(
    main,
    textvariable=validation_result_var,
    font=("Segoe UI", 12, "bold")
).pack(pady=4)
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🎛 Step 11: Controls

controls = ttk.Frame(main)
controls.pack(pady=8)

ttk.Button(
    controls,
    text="✅ Validate",
    command=validate_email,
    style="Action.TButton"
).pack(side="left", padx=4)

ttk.Button(
    controls,
    text="📤 Export History",
    command=export_history_txt,
    style="Action.TButton"
).pack(side="left", padx=4)
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🗄 Step 12: Email History Vault

vault = ttk.LabelFrame(
    main,
    text="Email History Vault",
    padding=10
)
vault.pack(fill="both", expand=True, pady=10)

history_list = tk.Listbox(
    vault,
    font=("Segoe UI", 10),
    height=10
)
history_list.pack(fill="both", expand=True)
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⚙ Step 13: App Options

ttk.Checkbutton(
    main,
    text="Dark Mode",
    variable=dark_mode_var,
    command=toggle_theme
).pack(pady=6)
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▶ Step 14: Run the App

root.mainloop()
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This starts the Tkinter event loop and launches your application.

🎉 Final Thoughts

You now have a fully functional email validation desktop app with:

Regex validation

MX record checking

Multithreading

History tracking

Export functionality

Dark mode

Email Validation Tool

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