This is already possible. You need to correct your user provisioning. You can do this in your SAML configuration. The email you receive in the SAML response needs to go to the "Name” and "Email” attribute if you're using email address as the username.
If you're using another property (like I see in the image the part of email address before the "@domain.com”) as the username, you need to use the xml tag of that property in user provisioning OR use custom user provisioning to find the correct account and update it with properties from SAML response and log your user in.
Hope this helps