When 'sending' email, outlook will send files in an unreadable format 'winmail.dat' if it thinks the message is formatted as rich text.
In brief you need to change your default message format to 'html or plain text' then also update/delete any contacts that have the default already set incorrectly.
Here is a website that goes through all the settings in detail: https://blog.gimm.io/how-to-fix-winmail-dat-attachments-in-outlook/
For incoming winmail.dat files you should request the sender fix the problem. SurgeMail does have a feature to try and 'convert' the files, but this is not as reliable as fixing the problem at the sending end. (See setting g_winmail_fix)