Morning (I´ve omitted the Good) Eva,
I have no magic - the only thing I can think to try is to completely uninstall Avast and then reinstall it.
Your computer knowledge is at least as good as mine, probably better. Whilst you/we await expert help
may I ask if you have a satisfactory email workaround just for now?
Do not give up - even if it were say, a hardware problem, I reckon someone here will crack it soon.
My regards