Whether both are possible at the same time depends on the type of forwarding.
Additional mail forwarding (temporary or «hold mail»)
An additional forwarding of mail cannot be used in parallel with the ePost ScanningService. As long as such forwarding is active, you cannot use the ScanningService. Delete the existing forwarding first. You can do this yourself in Swiss Post's customer centre.
Change of residence with change of address
A change of residence is a separate process and not an additional parallel forwarding. After the change of address with Swiss Post, register the new address in the Swiss Post-App under «My digital mail», verify it and activate the ScanningService for the new address. Important: the address registered in the Swiss Post-App, «My digital mail» section, must match the address on the letters. Only in this way is delivery guaranteed.
Note: If the original forwarding concerns several people, request a forwarding to a different address for the other people.