If you have applications or gateways created with the File Format API (FFAPI), they will continue to work with Microsoft Exchange Server. You need to plan what to do with them when all of your postoffices have been migrated to Microsoft Exchange Server. The Connector postoffice can be considered to be just like any Microsoft Mail 3.2 postoffice for purposes of FFAPI applications and gateways.
Important You need to use the -md switch on FFAPI to disable the mailer. If you don't disable the mailer, mail going through the Connector postoffice may be returned as undeliverable.
After all postoffices are migrated to Microsoft Exchange Server computers, the FFAPI applications can continue to be used with the Connector postoffices as long as the Microsoft Mail Connector interchange and MTA services continue to run. Contact the application vendor to see if they have native Microsoft Exchange Server applications.