Currently, when you install Magnolia, each module may ask the admin to perform additional steps like setting SMPT info. This info is displayed right on the install screen. To perform the steps requested, one would need to log into the system, hence leaving the install screen. Thus, the messages are gone.

I suggest to look into alternate mechanisms - maybe create a content page on the fly that contains this info with direct links to the config or even form fields for the missing info.