Quite some work done here.

src/Tech/Service/EmailVerifier.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace App\Tech\Service;
+
+use App\Tech\Entity\User;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Bridge\Twig\Mime\TemplatedEmail;
+use Symfony\Component\Mailer\MailerInterface;
+use Symfony\Component\HttpFoundation\Request;
+use SymfonyCasts\Bundle\VerifyEmail\Exception\VerifyEmailExceptionInterface;
+use SymfonyCasts\Bundle\VerifyEmail\VerifyEmailHelperInterface;
+
+class EmailVerifier
+{
+    public function __construct(
+        private VerifyEmailHelperInterface $verifyEmailHelper,
+        private MailerInterface $mailer,
+        private EntityManagerInterface $entityManager
+    ) {
+    }
+
+    public function sendEmailConfirmation(string $verifyEmailRouteName, User $user, TemplatedEmail $email): void
+    {
+        $signatureComponents = $this->verifyEmailHelper->generateSignature(
+            $verifyEmailRouteName,
+            (string) $user->getId(),
+            $user->getEmail(),
+            ['id' => $user->getId()]
+        );
+
+        $context = $email->getContext();
+        $context['signedUrl'] = $signatureComponents->getSignedUrl();
+        $context['expiresAtMessageKey'] = $signatureComponents->getExpirationMessageKey();
+        $context['expiresAtMessageData'] = $signatureComponents->getExpirationMessageData();
+
+        $email->context($context);
+
+        $this->mailer->send($email);
+    }
+
+    /**
+     * @throws VerifyEmailExceptionInterface
+     */
+    public function handleEmailConfirmation(Request $request, User $user): void
+    {
+        $this->verifyEmailHelper->validateEmailConfirmation($request->getUri(), (string) $user->getId(), $user->getEmail());
+
+        $user->setIsVerified(true);
+
+        $this->entityManager->persist($user);
+        $this->entityManager->flush();
+    }
+}

src/Tech/Service/UserChecker.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace App\Tech\Service;
+
+use App\Tech\Entity\User;
+use Symfony\Component\Security\Core\Exception\CustomUserMessageAuthenticationException;
+use Symfony\Component\Security\Core\User\UserCheckerInterface;
+use Symfony\Component\Security\Core\User\UserInterface;
+
+class UserChecker implements UserCheckerInterface
+{
+    public function checkPreAuth(UserInterface $user): void
+    {
+        if (!$user instanceof User) {
+            return;
+        }
+
+        if (!$user->isVerified()) {
+            throw new CustomUserMessageAuthenticationException('Your email address is not verified.');
+        }
+    }
+
+    public function checkPostAuth(UserInterface $user): void
+    {
+    }
+}