What tools? Are you going to go the Mailman route, creating a hundred useless command line tools alongside a custom web-based configuration engine, sitting atop a complex database schema, possibly using a relational database backend? Almost every other option effectively boils down to that, and it's horrible.
The limitations of an ASCII configuration file is its virtue! Often times they turn into domain specific languages. In which case, use sendmail.cf as your north star and head south.