High Sierra Topix

Sent a birthday message out on the 22nd and is still in my outbox, and another that was
sent the 23rd and that one has been received by the other member.
Why is there such a lag time?

I'm not sure how it works but my guess would be that the person you sent it to just hasn't realized it is there and opened it yet.

Private messages remain in the Outbox until they are opened by the intended user. So I concur with Gary - the recipient hasn't read the PM yet.

Thanks