You need to check your settings, on your side. It can sometimes be just something small. The easy way to make sure yours is right compare it with your husband’s.
I have a comcast account and meeting requests arrive in my mailbox with the information as text, just as you discribe; however there is also an attachment and if I open the attachment it opens a regular outlook meeting request. Tell him to look for the attachment. Does he have Outlook installed on his PC?