Overview

A given person reportedly became a member of more than one list without confirming the subscriptions via email, as would have been expected.

Solution

The default behavior is: if the user subscribed to several lists at the same time and confirmed to any one of them, ListManager will confirm the subscription to all lists that were pending confirmation.

The default behavior can be changed in the lmcfg.txt file by setting the $enforce_single_confirmation parameter:

###########################################################
#
# $enforce_single_confirmation: This parameter specifies confirmation link behavior.
# A member who subscribes to a list gets a 'confirm' status link in an e-mail
# for each list he subscribed to. With the setting set to false, clicking a link
# in the e-mail confirms all subscriptions which are pending confirmation.
# With the flag set to true, only one list (the one included in the link) is being confirmed.
#
###########################################################

To have the users confirm each subscription individually, set  $enforce_single_confirmation = "true".

Don't forget to restart the LM services after saving the changes.