1. Personally, I like having them as-is.
2. Individual users can switch them on/off as they wish, either via
the web interface or via email. (It might be good to include wording
about both methods in the initial welcome message sent to new subscribers.
Perhaps it might also be good to include the same in monthly reminders.)
3. Consider shifting the reminder date to something other than the
beginning of the month (which is Mailman's default). People on many
Mailman-operated mailing lists tend to get inundated on the first
day of each month, so perhaps this might make the traffic more palatable.
---rsk