Start Email Magic Link Enrollment

curl --request POST \
  --url https://api.authsignal.com/v1/client/user-authenticators/email-magic-link \
  --header 'Content-Type: application/json' \
  --data '{
  "email": "<string>"
}'

{
  "challengeId": "<string>",
  "userAuthenticatorId": "<string>",
  "userId": "<string>"
}