The properties of the message "RE:XXXX" have been changed- error

I keep getting an error when I try to exit an email in Outlook that I have used the “Set Regarding” tool on to tie the email to a record in CRM 2015 Online. Every time I go to close an email after using set regarding it has a pop up box that says "The properties of the message "RE:XXXX" have been changed. Do you want to save changes to this message?" Is there any way to disable this message so I don't have to see it anymore?

Thanks