OK, I spontaneously checked C:\Users\jorgk\AppData\Local\Temp and found four left-over temp files :-(
nsemail.eml with versions -1 and -2 and a nsmail.eml. The former three only contained headers, the latter one contained a message attachment, so message which I had sent out as an attachment. So yes, there must be some hole somewhere.
OK, I spontaneously checked C:\Users\ jorgk\AppData\ Local\Temp and found four left-over temp files :-(
nsemail.eml with versions -1 and -2 and a nsmail.eml. The former three only contained headers, the latter one contained a message attachment, so message which I had sent out as an attachment. So yes, there must be some hole somewhere.