Problem statement
Using the built-in message provider for MFA, there is the message :
There is a maximum of 100 messages per tenant during the entire tenant lifetime. New codes are not received after reaching the 100 message limit.
This article describes how to determine the number of MFA messages remaining.
Solution
There is no way to retrieve the number of messages left. Please note that the built-in provider is designed for testing purposes only. If there is a need for a higher number of messages, a custom provider must be configured.