Hi, so I tried to send a file on MSN 3 on a Windows 98 VM, and the file wont send. It will give me a error.
Proof:
Unfortunately these older versions of Messenger don’t have fallback to the switchboard to be able to send through the Escargot (Messenger) server. In order to send files on these versions, you’ll need a public IP address or be on the same network, as well as have ports 6891-6900 TCP open in any firewall (one for each simultaneous file transfer) on the sender side.
You could also use a VPN or something so that both parties are on the same network.
At the time (circa ~2001) the early router manufacturers like Linksys implemented application layer gateways (ALG) for MSN file transfer which would automatically change the IP address and make this work. For the most part, modern routers no longer have this capability.
My apologies, I got going down memory lane there and forgot to address the question in your subject line! 
I guess technically this could be possible if the server were to manipulate the file transfer request with its own file transfer IP and port, and then either proxy or provide a link at the end of the transfer to the recipient. Although in all honesty, I don’t think anyone is very likely to pick up that project.
tl;dr you have to open ports 6891-6900 (ranged ports), for now anyway, it will prob’ get fixed sooner.
PS: i use WFW, to change settings i use WFWw/AD, do i need to make a unblock rule for Inbound or Outbound connections? or even both???
As far as i know you can just allow the app on the Windows Firewall and it should work.
Watch out of you have a router in between (Between the modem and the endmachine, and are using double NAT (2 DHCP servers) ), then you should portforward from your public modem to your router.