MagicBell accepts emails and external IDs (strings) as unique identifiers for users, though the way you send notifications to a user depends on how you identify users in your app.
If your app allows users to update their email addresses, we recommend to use external IDs.
There are a number of benefits to choosing external ID over email as an identifier:
- External IDs are generally more robust, persistent, and can be linked to your app's DB records.
- Should a user's email address change in your system, you can update it in the same request to create notifications, removing the need to separately update the email address.
- When sending both
emailandexternal_id,emailwill simply be an attribute for the user that's used to deliver email notifications.
If you use an integer to identify users, remember to cast it to a string.