The MSG appliance has stopped sending emails out to external domain addresses
Sending emails to internal domain addresses works without issue
Receiving emails from any sender works normally
Outgoing connector is showing errors about invalid certificates
The problem might be caused by an invalid or expired certificate on the MSG-appliance
To verify the active certificate:
Log in to the MSG web UI
Select the System-tab on the top of the page
Navigate to System->Certificates->Services using the menu on the left-hand side
Note which certificate is in use for the different services
Navigate to System->Certificates->Certificates
Verify the validity of the certificate(s) that is in use
If the wrong certificate is in use, it can be changed on the Services-page from step 3. Use the dropdown menus to change the certificate for all services and click Save changes.
If the certificate in use has expired, use the Generate Certificate Request-button on the Certificates-page from step 5 to start the process of adding a new certificate to the MSG-appliance. Use the created certificate request with an acquired certificate from a certificate vendor to make a new certificate for the MSG, then import the new certificate into the appliance using the Import-button, also on the Certificates-page from step 5. After this, use the instructions mentioned above to change the active certificate for all services, and save the changes.