Real-time status of 9 SMTP (mail submission) servers worldwide. We probe the 220 banner, send EHLO, and check STARTTLS + AUTH capability for smtp.gmail.com, smtp-mail.outlook.com, smtp.protonmail.ch, and more.
Run php artisan mti:seed-smtp to seed the initial list, then php artisan mti:verify-smtp --limit=20 for the first health check.