See this suggestion from the source: https://www.ic3.gov/media/2015/150827-1.aspx
Create intrusion detection system rules that flag e-mails with extensions that are similar to company e-mail. For example, legitimate e-mail of abc_company.com would flag fraudulent e-mail of abc-company.com.
Does barracuda has some kind of protection for it?
It seems to me almost impossible, because what is 'similar'. There are hundreds of possibilities.