Thanks again DavidR. Your hints are valuable to me even though you don't use SeaMonkey client.
I deleted the message it yesterday.
So I decided to recover from the yahoo trash folder (on their server) to my local inbox in SeaMonkey as an experiment. Today's alert did a bit different trojan id, perhaps due to new definitions, perhaps due to me participating in the avast's community, who knows.
2/21/2014 10:43:18 AM Incoming email 'Barclays transaction notification #799654' From: "Barclays Bank " <reports@barclays.net>, To: < several email addresses here >|>Payment receipt Barclays PA77392733.zip#1654153047|>Payment receipt Barclays PA77392733.exe [L] Win32:Zbot-SQW [Trj] (0)
While moving file to chest, error occurred: The system cannot find the file specified
File was successfully deleted...
No, neither before, nor today is there any ***VIRUS*** flag on the subject/title (see picture), but when I open the message (no, I don't click the .zip file, don't worry), X-Antivirus lines are there - see picture.
Not sure if you're right that as SeaMonkey was moving it to junk, Avast couldn't get at it. Today I let it sit before sending to junk mail and the "error occured", and still, the "successfully deleted" is not correct. That may be Avast problem or, as you mentioned, SeaMonkey structure. Oh, well...
I wonder if Thunderbird-Avast pair would behave in a similar manner.