If you lost your mailman installation and want to switch to another service, and you still have the mailman config files, then you can extract information from the file using python pickle.
import pickle
f=open('config.pck','rb')
a=pickle.Unpickler(f,fix_imports=True,encoding='ISO-8859-1').load()
for email in a['members']:
print(email)
;){kind=link}