Er, I don't know how to post a picture of this, but I'll try to describe... and anyone whom is reading this and it's already made as a bug post, then can you, uh... lock it or delete this? Thank you...

Okay, what I was saying with the bug.. my outbox says I sent to certain people when I am RPing... but once a great time has past, I'll ask if they get it, and they honestly say no. So, I'm thinking that my mail isn't being sent, even as my outbox says it was sent, but the other person says otherwise.. just didn't know if that's just a problem with me, or if it can be fixed... S-sorry! ><'

If it's showing as sent in your outbox, then it's definitely sent.
The only cases where it wouldn't have sent is if it's not showing in your own outbox messages

how long do you wait before asking them if they've seen it out of curiosity?

Well, at one point it was a month, and I finally asked them.. they said they didn't get it. But I know them well enough that they usually answer an hour later at most. It might be how much I have in there, I might need to clear out some of it.

They recieved it. If they read it or not is a different matter.

Okay, thank you. Sorry for the troubles..