package = email
prefix = package.__name__ + '.'
for importer, modname, ispkg in pkgutil.iter_modules(package.__path__, prefix):
    print('Found submodule %s (is a package: %s)' % (modname, ispkg))
module = __import__(modname, fromlist='dummy')
print('Imported', module)
List all the modules that are part of a python package?