I managed to locate the installation archive for FrontDoor 2.33.mL (DOS) and have made it available for download here. This is a self-extracting archive. Run it inside a DOS compatible session. You can also download the installation archive for FrontDoor 2.33.mL (DOS + OS/2) here.
DOS
FrontDoor 2.32.mL
FrontDoor 2.32.mL has been released! This release features a native 32-bit OS/2 version as well as a DOS version. Click here to download the update.
FrontDoor 2.26.SW
FrontDoor 2.26.SW (Shareware) has been released! This release features a native 32-bit OS/2 version as well as a DOS version. Click here to download the update.