I am suddenly in a situation where emails sent to hotmail addresses are not being received, yet I do not get a message saying that they have not been delivered.
Are you able to tell if there is problem at my end, thanks.
I can take anywhere from several hours to a week for the typical residential ISP to let you know if an email that you sent has failed to be delivered.
If it's a residential you can try calling them but probably won't get much help.
If you are sending as the domain listed in your post from a business connection you should check the mail server logs so you can see specifically what happened to the email or why it's being blocked / deferred.
Check your Trash and spam folders for notices from mailer-daemon for clues too.