"Sent" v. "Outbox" (California)

Hi,
My previous outgoing PM's all landed in the Sent box once sent, but a recent msg., sent twice, remains in the Outbox thus I'm unsure of delivery status.
Advice por favor...?
Thanks...
My previous outgoing PM's all landed in the Sent box once sent, but a recent msg., sent twice, remains in the Outbox thus I'm unsure of delivery status.
Advice por favor...?
Thanks...