How are people synchronising non gmail or outlook email accounts now?

Hello, My team has been using Tealeaves and another windows based email attacher that were both sourced through the marketplace page many years ago. Tealeaves has now gone end of life and one of my team who uses a windows machine needs to upgrade his computer. So we need to install a new app to sync his client emails with their file in InfusionSoft. However there doesn’t seem to be any available in the marketplace and the chat people weren’t able to help. I know there is Email Sync but it won’t work as we have our own email server through Netregistry and don’t run on a microsoft or gmail email server. Can anyone assist? Many thanks, Diana