You could try adding their email address to your safe senders list. This can be found by logging onto your email account and clicking on your username at the top right then going to settings > Mail > Safe Senders.
thanks just tried to put my daughter's email in safe sender which is gmail.com but get an error message saying "gmail.com domain is already in Block senders list " really haven't a clue as to what this means
It means that you have somehow blocked all Gmails. Go to your blocked senders list in Settings> Mail > Blocked Senders and delete the block.
One of the 3 options on webmail when blocking spam is "mark as spam and block domain". Perhaps this is what you have done for a spam email that supposedly came from the gmail.com.