[backstage] Emails appearing twice?

[Christopher Woods]

I've noticed various emails appearing twice in the past day or so on the
backlist list. Notably, my "News 24 moves to Astra 2A" has just appeared in
my inbox, even though I sent it earlier today.
 
The order of emails received is also a little confused sometimes... And is
it me, or do emails always take a while to come through on the list? I don't
have this problem with other lists, so I'm assuming some kind of virus
scanning or background processing... What gives?