Sending Rules

DripDrop uses explicit policy flags instead of broad mode labels. Each sequence step can opt into the rules it needs.

Unsubscribe Headers

Email steps can opt into RFC 8058 headers:

%{
  "unsubscribe_headers" => true
}

or:

%{
  "unsubscribe" => true
}

When enabled, configure :unsubscribe_url_builder so the host app can return a one-click unsubscribe URL. DripDrop inserts the RFC 8058 headers before provider delivery.

Reply Behavior

Replies are recorded as provider events by default. To pause an enrollment after a reply:

%{
  "reply_behavior" => "pause_enrollment"
}

Hosts can replace the default behavior with config :dripdrop, :on_reply. The callback can be a {Module, :function} pair or an arity-2 function called with the normalized event and step execution.

Recipient Verification

To require the host app to mark a recipient as verified before a send:

%{
  "require_verified_recipient" => true
}

Dispatch checks enrollment.data["recipient_verified_at"] and skips the send when it is missing.

Daily Caps

Daily caps defer sends after a sender mailbox reaches its configured limit:

%{
  "sending_rules" => %{
    "daily_cap" => 50,
    "timezone" => "America/New_York"
  }
}

Caps may be set on the step or adapter, either under "sending_rules" or as a flat "daily_cap" value. Step config wins when both are present. Invalid caps fall back to 50 and valid caps are capped at 500.