The recipient has to read it, then it'll be moved to your sent box. If they don't read, it'll linger in the outbox.
The thoughts I've expressed in the above post are carefully considered and offered in good faith.
And friendliness towards the world is happiness for him who is forbearing with living beings. -- Ud. 2:1
To his own ruin the fool gains knowledge, for it cleaves his head and destroys his innate goodness. -- Dhp 72