E-mail message rejected

[REDACTED]

I am new to this forum and also new user of avast. I installed and registered the program one month ago and so far so good. But yesterday I received an e-mail from one of my friends in Spain, which I regularly having e-mail contacts with and suddenly his e-mails are rejected by the avast giving me heuristisk warnings. Can anyone explain this to me and help me how to accept e-mails from adresses that obviously avast sees as spam, or 

[Lisandro]

avast Heuristic email module could be fully configurated according to your needs.
Left click the avast icon, click Details button, choose Internet Mail at left, click Customize button at right. Go to Heuristic tabs of settings and configure.
Do the same for Outlook plugin.

There isn't a white list for emails senders.
Welcome to avast forums.