180 way of doing

No more hooks, instead I use users preferences and cronned task

Producer set user preferences following this convention:

For each list identifier by ID
* set a preference for app=user_mailinglist, key ="do.sub.${ID}",value=mail
* a cron will seek this preferences, send email to mailing list server and
* change preference to key "sub.${ID}"

The same with key="do.unsub.${ID}"