Log in to Azure portal, navigate to Azure Active Directory and select Enterprise applications in the left sidebar.
Click + New application.
Click + Create your own application, name it “Missive”, select “Integrate any other application you don't find in the gallery” and click Create.
Click Single sign-on in the left sidebar, then select the SAML method.
Logged in as an admin in Missive, open your Organizations settings, then the SSO tab, copy the required fields and paste them in the Azure Basic SAML Configuration form as shown below.
Copy the Login URL field and paste it in your Missive SSO settings in the Entry point field.
Download the Certificate (Base64), copy its text content, and paste it in your Missive SSO settings in the Signing certificate field. You may need to rename the downloaded file to a .txt extension in order to easily copy the content.
Click Users and groups in the left sidebar, then add all users who should log in to Missive.
In your Missive SSO settings, enable Single Sign-On.