Module hooks are the event hooks that fire when something happens inside Mumara Campaigns — register a callback with add_hook('HookName', $priority, $callback) and your code runs every time that event occurs.
The reference catalogs every available hook by area:
Contacts & lists — AddContact, EditContact, DeleteContact, their Automation* variants, list CRUD, ImportList/ExportList, custom fields, and segments.
Campaigns — broadcast lifecycle (AddBroadcast, ScheduleBroadcast, StartBroadcast, PauseBroadcast, SystemPauseBroadcast, CompleteBroadcast), drips, triggers, and split tests.
Infrastructure — sending domains (verification hooks like SendingDomainVerified and SendingDomainDnsFailed), sending nodes/SMTP, bounce addresses and rules, feedback loops, and web forms.
Email events — EmailOpened, LinkClicked, the *PostProcess hooks, and the Timeline tracking hooks.
System — user and package hooks, AfterCron, CreateNotification, taskComplete, plus the filter-style plan_tabs, plan_sections, and plan_hide hooks that let addons extend the Plan & Usage page by returning descriptors instead of just reacting.
The shape of $vars differs per hook — sometimes a model object (e.g. DeleteContact receives the Subscriber model), sometimes an array (e.g. AddContact provides subscriber and fields keys) — so check each hook's entry before assuming. Also note a few hook names contain historical typos that must be used exactly as documented: EditSpingTag, AddFeebackLoop/EditFeebackLoop/DeleteFeebackLoop, and SendingDomainDKIMGenerted.