CommuniGate Pro applies routing rules not only to addresses in incoming messages, but to all addresses it processes. If you have rerouted the postmaster account to some other account abc, then all attempts to log in as the postmaster will cause the Server to try to open the abc account. If you provide the correct password (i.e. the abc account password), you will be able to log in, but you will have the access rights granted to the abc account, not to the postmaster account.

You still can log into the postmaster account even if the postmaster name is redirected to a completely different address. Use the following name instead of the postmaster name: abcd@postmaster.local.

This address is always routed to the account postmaster. Use the regular postmaster account password with this string.

For more details on the .local routing, check the Local Delivery Module section.