Mailman error: You must GET the form before submitting it.
Some colleagues of mine tried to subscribe to an OSGeo List recently and ran into this error:
grass-user Subscription results You must GET the form before submitting it.
Problem: no error message provided nor their susbscription actually issued.
The forms (Name, Email, double password) were filled in.
In /var/log/mailman/* I cannot identify a related error.
What might be missing?