You may well already be doing so, but I managed to get it to work by only putting the first part of my username in, leaving off the '@gmail.com' part
Yes generally username will only be the first portion thats needed, your actual username and as you are placing the server details such as smtp.gmail.com in it will auto resolve username to domain name therefore no need to put the @abc.com in after. If you have set to receive alarms as well then you can receive an alarm from 'motion event' for example + 1 with pic of cap
HTH