Question about Xbox Live communication settings

So I play a lot of Rainbow 6 Siege and because of that I've had to set my communication settings to "unable to be contacted/messaged by people that are not on my friends list". If you play the game, you understand. The community can be so very toxic and I got tired of the random messages from trolls. It's been a huge improvement in my Siege experience but I'm wondering what happens if I switch back to being able to communicate with anyone on Xbox Live.

Two things. One, will all the messages that I've been sent while communications are off come flooding in? Because I know that you can still send a message to someone with communications turned off but they just won't know because it never arrives.

Two, does creating an LFG Siege post on Xbox Live temporarily allow me to get messages from people when I have communications turned off? Because sometimes my buddy and I would love to pick up an additional person to play with but I've never messed around with the LFG section of Xbox Live. I feel like if I've set my communications to be limited to only friends, then creating an LFG post would be pointless because I'll never know if someone wants to play with me.

Thanks.

:)