Using that logic Sent means sent. If you wanted to keep it why did you 
send it ;)

But seriously, in the he-said-she-said business I work in, they say 
never delete any email. The emails may have been dealt with which is 
why they are not in the current saved folder.

There are a whole set of messages that you accumulate that you don't 
want to file but you want to keep, otherwise you would have thousands 
of folders.

Often a piece of information is irrelevant at the time and deleted, 
but is required a month or two later.

The trash (or whatever folder you designate as keep-trash) folder 
would get bigger and bigger to the point of having to rename it to 
keep-trash-01, keep-trash-02, etc.

It makes more sense to just include it in the monthly maintenance; I 
suppose it is about making the mail more manageable.

Trash means trash.  Meaning "I don't want this message anymore".   
Archiving trash makes no sense.  If you really want an archive of your 
messages, either don't delete messages, move them to a save message 
folder, or don't use a trash folder and hide deleted messages.

The monthly maintenance renames the sent folder to sent-items-<date>.

Please can the same thing happen to the Trash folder.

In the same way I like to see what I have said, I want to remember 
what other people have said to me.



[This is not a support question, this is a request for an enhancement]