I have been running Avast awhile now. It has always marked the comment [Infected - Avast] on the subject line of emails. In the last two days Avast has announced a few of those sober.ab virus/worms and quarantines the attachment but Avast is no longer making the notation in the Subject area. I must have undone a setting somewhere but I can’t find it. What do I need to tick to make this work again?
See the two Heuristic tab of settings into Internet Mail provider and, if you use MS Outlook, Outlook plugin of avast.
There, specially in the first tab, you can set this 
Welcome to avast: the most configurable antivirus round 