Public bug reported:
This can be prevented by refusing to pend a subscription when one is already pending, but that means if a subscriber loses or doesn't receive the confirmation request email, she has to wait PENDING_REQUEST_LIFE (default 3 days) before she can request another.
It can also be avoided by setting the list's subscribe_policy to Moderate, but that may not be desirable in many cases.
Because of these considerations, I will implement the refusal to pend a subscription when one is already pending, but make that depend on a new REFUSE_SECOND_PENDING mm_cfg.py setting.
** Affects: mailman Importance: Medium Status: In Progress
** Branch linked: lp:mailman/2.1
** Changed in: mailman Status: In Progress => Fix Committed
** Changed in: mailman Status: Fix Committed => Fix Released
** Changed in: mailman Assignee: (unassigned) => Mark Sapiro (msapiro)