The antonyms for the phrase "sending invitation" could be "denying invitation," "rejecting invitation," or "refusing invitation." When someone denies, rejects, or refuses an invitation, they are indicating that they cannot or will not attend an event or gathering, that they do not want to participate or help plan the event, or that they do not want to be involved in the activity. Although these antonyms may have negative connotations, it is important to remember that not everyone can say "yes" to every invitation and that people have their own priorities, schedules, and preferences. It is always best to respect people's decisions and opinions about attending events or gatherings.