Hi @castansa , to enable OTP for sign in custom policy integrated with Sendgrid, you need to add the OTP technical profiles to the ClaimsProviders element in your policy. The GenerateOtp technical profile generates a code for the email address, and the VerifyOtp technical profile verifies the code associated with the email address. You can change the configuration of the format and the expiration of the one-time password. Please let know if you have any questions and I can help you further.
If this answer helps you please mark it as "Verified" so other users can reference it.