Currently it is only possible to set silent = true or false at the document level. There are scenarios where recipient level control is needed, e.g. for embedded signing. If recipient A is embedded signing and recipient B is signing from email, we wouldn't want recipient A to also receive email notifications.

Related to the personal message at recipient level feature request, which is also currently document level only: https://pandadoc.uservoice.com/forums/926629-ideas-to-improve-pandadoc/suggestions/43994823-customize-select-personalize-email-messages-for-mu#comments