The use of Azure Email Communication Service by SMTP Add-on Service

Scenario: I develop SMTP Add-on Service (took this term from http://Integrate%20Exchange%20Online%20with%20an%20email%20add-on%20service). The mailflow: 

• Sender (user in Exchange Online tenant)
• Exchange Online servers
• to SMTP Add-on Service via SMTP
• to another SMTP server for final delivery.

The SMTP Add-on Service will process all outbound emails from the customer tenant. Emails can be big enough (the default limit in EO is 150 MB, if I am not mistaken).

We are considering to use the https://learn.microsoft.com/en-us/azure/communication-services/concepts/email/email-smtp-overview.

Questions:

• Is it the correct use of the Azure Email Communication service?
• Any limitations for using Azure Email Communication service in my scenario?

Thanks.