Which email providers work with this? Do I need something special?

Any standard SMTP provider — the setup page itself lists Gmail, Outlook, SendGrid, or your own mail server. The common ports are 25 for plain, 587 for TLS and 465 for SSL, and you pick the encryption that matches your provider's settings. If you've ever configured an email client on a phone or desktop, you've already done 90% of this. The one thing to watch is providers that require app-specific passwords for third-party SMTP use — Gmail does, so generate one rather than using your regular password.