Restricting data usage when i tether

Hello ,

I have just moved to a new house. Sadly now i find out that this wifi provided to me here has something that is not allowing my mail app to work on my mac. (i looked it up online and it seems its common for some people to restrict this on the wifi they provided god knows why)

Anyway everything else works normally with this Wifi, but i must tether from my iphone to my mac to work with the mail app.

Is there a way to specify which apps on the mac are allowed to use the wifi when i do data tethering? I am worried one day i work with mail and if i connect for a long time it will suck all the my monthly data

Regards,