-cust_bill, svc_acct, cust_pay, or cust_pay_pending object).
+cust_bill, cust_pay, cust_pay_pending, or svc_(acct, phone, broadband,
+domain) ). If the object is a svc_*, its cust_pkg will be fetched and
+used for substitution.
+
+As a special case, this may be an arrayref of two objects. Both
+objects will be available for substitution, with their field names
+prefixed with 'new_' and 'old_' respectively. This is used in the
+rt_ticket export when exporting "replace" events.
+
+=item from_config
+
+Configuration option to use as the source address, based on the customer's
+agentnum. If unspecified (or the named option is empty), 'invoice_from'
+will be used.
+
+The I<from_addr> field in the template takes precedence over this.
+
+=item to
+
+Destination address. The default is to use the customer's
+invoicing_list addresses. Multiple addresses may be comma-separated.
+
+=item preview
+
+Set to true when preparing a message for previewing, rather than to actually
+send it. This turns off logging.