[Mailman-Developers] Error during installation of postorius

I tried installing the postorius , and on logging in I am facing an error "SMTPRecipientsRefused at /accounts/login/" what would be causing the problem? on reading the docs I found that we should add the settings of postfix in mailman.cfg file.but even on adding the settings , problem persist. Thank You -Nikhil Rayaprolu