If I archive a message from someone who has ghosted, then they suddenly return. Are they able to message in the same conversation, or would they have to create a new conversation with me?
They can message you in the same conversation.
Okay, and will that remove the conversation from my archives and give me a notification that I have a new message?
Yes 
Ditto if you delete the conversation, btw. Their response will remove it from the trash and notify you as normal.
Awesome, thanks Kim.
A note on the PM archive function... I use it heavily as every time I reply to a message, I immediately ‘archive’ that message. That takes it out of my Inbox so only unreplied messages remain. When someone replies to one of my archived messages, it reappears in my Inbox. It’s a good organisational tool for me.
You are on: Forums » Help » Question about archived messages
Moderators: Mina, Keke, Cass, Claine, Sanne, Dragonfire, Ilmarinen, Darth_Angelus