Microsoft Exchange mailbox almost full

For the company I work for, we have an account and used to use Windows Live Mail 2012. Recently I’ve transferred everything over and am now using the free version of eM Client. I keep receiving an email from Microsoft Exchange saying our inbox is almost full, I’ve since deleted over 4000 emails but I’m still getting this warning come through. Any help please?

Maybe ask your provider for assistance.

BTW if you are using eM Client for your company email, you need to purchase a Pro License as using a Free License is a violation of the license agreement.