Possibly. Once I understand precisely how it works, I'll come back and post... however I doubt you'll need to resend it. Any that I have sent have worked, and always worked their way to the Sent Box in time. Possibly (and this just a guess), "Outbox" means it hasn't been collected. You could test this by checking the status of the PM you sent to me.
"Do not force others, including children, by any means whatsoever, to adopt your views, whether by authority, threat, money, propaganda, or even education." - Ven. Thich Nhat Hanh
"Whether I were to preach in brief, Sāriputta, or whether I were to preach in detail, Sāriputta, or whether I were to preach both in brief or in detail, Sāriputta, rare are those who understand." (A I 333, Sāriputtasutta)