dnspython >=2.0 requires Python >=3.6 and won't work with Mailman 2.1. ./configure should check for dnspython <2.0 and mention this requirement of not found.
dnspython >=2.0 requires Python >=3.6 and won't work with Mailman 2.1. ./configure should check for dnspython <2.0 and mention this requirement of not found.