Steps to reproduce:

1. Create user macros which contains Email address (https://www.zabbix.com/documentation/current/manual/config/macros/user_macros)
2. Add this macros to Users-Media-Email. According to documentation we can use it there (https://www.zabbix.com/documentation/current/manual/appendix/macros/supported_by_location_user).
3. Save configuration and get an error: Invalid email address "{$USER_MACROS}".

Result:
Create macros:

Add this macros to Users-Media-Email:

Expected:
Expected that user macros will be accepted in Users-Media-Email field.
By the way, it's possible to use user macros in another Users-Media types.