The ability to send an internal notification to team members when an email doesn’t send - usually from attachements being too big.
Currently there is only a notice that shows on the email activity on the eligible objects. However, this is obsolete for busy teams that are not constantly reviewingin records and if an email was sent successfully.
When sending from an emai client if an emial is not delivered there is some sort of return notice, however, this is not the case with HubSpot and would be a very beneficial feature.