I haven't deleted a single valid email yet. I just archive them. As
for deleting the last one from a thread, that would require that noone
snips the previous talk in his reply, which many people including me,
do. It would also require that everyone replies to the exactly
previous email, so that you keep a full snapshot of the conversation
in the last email. That is ofcourse if you do care about such
meticulous archiving.
Gmail has been subtly suggesting that we don't *need* to delete
anything, and many people think it's a plot so that we keep more and
more information in here for Them to access at their leisure. Maybe
they're right. Or maybe it's just a marketing scheme. Saying "you have
so much space you don't need to delete an email ever" may be an
exageration, but it plays on peoples previous (bad) experiences with
email, where storage is an issue. We all have had to keep deleting
email from our email server at some point, so Gmail's catch line will
work wonders on us. Ofcourse as soon as you start using it you forget
about the space and start appreciating the well thought-out interface
and functionality itself, which is what we've been collectively doing
here at gmail-users :)
Fanis