This connection requires the licensing of the Email to SMS module.
Port 25 have to be forwarded from outside of your network to the SMS Gateway
Log in to the Exchange Control Panel by selecting the URL( https://outlook.office365.com ) of Exchange Online.
Change to Message flow - Send connectors
Add a new send connector by clicking on the "+" symbol.
Choose From: Office 365 and To: E-Mail Server of your organisation
Choose Only E-Mails sent to this domain and add the domain sms.local with a click on +.
This domain, sms.local, has to be configured on the SMS Gateway under Configuration > Email to SMS in the input area Accepted Email Domains.
Add the domain your SMS Gateway can be accessed or add a static ip address.
Add All digital certificates, including selfsigned certificates as needed.
Conclusive Exchange Online will check th connection to your SMS Gateway with a test email. This email have to be sent to email@example.com.