Sure, lag could be a problem with some email providers, but you are not limited to email. From the site: "Deliver your tokens via email, text messages (SMS),

Sure, lag could be a problem with some email providers, but you are not limited to email. From the site: "Deliver your tokens via email, text messages (SMS), or smoke signs. You can embed Sendgrid, emailjs, Twilio, or any other framework you like to get the token to your user."