Mark Anderson wrote at 2012-04-06 15:17 -0500:
> On Thu, 5 Apr 2012 12:20:43 -0400, Antoine Beaupré <anarcat@anarcat.ath.cx> wrote:
> > Finally, I want to voice that I feel a "delete" key, even if it doesn't
> > delete mails, seems like an important part of a mail user
> > agent. Archiving mail is one thing, but for the love and respect of
> > sysadmins and the infrastructure they maintain, please consider adding
> > at least a way to *tag* those deleted emails.
> > 
> > Having the above keys being defined as standard in notmuch don't seem
> > like much to ask.
> > 
> > This may be a dissenting view here, but your mail is not that
> > important. :P
> 
> Hear! Hear!

I agree also.  I receive lots of mail that I never want to see again, nor do 
I want to see it still existing anywhere in my /home/user or in my backups.  
Someone might argue "but what if you decide you want it later" but I can use 
an Expires header to mark a message like "delete in 2 months", so I still 
have a chance to retrieve it within an amount of time I choose.

Somewhat related is the concept of saving spam messages.  I can understand 
the reasoning behind training bayesian filters, but I have never kept spam.  
I switched to bogofilter recently, and it was correctly filtering mail very 
quickly, perhaps within a few weeks (I did train it using non-spam messages).