"merging" folders Sent-Items Sent-Messages Sent

[Marc Roos]

I have a running server and would like to clean up a bit, and merge sent 
folders and trash folders etc.

Is this best done via the mailbox alias plugin like mentioned here? Or 
is there a better way? 

I prefer to have one folder listed at the client, and not "Unfortunately 
it also means that some clients will download the same mails to local 
cache multiple times."
https://wiki2.dovecot.org/Plugins/MailboxAlias


dovecot-2.2.10-8.el7.x86_64
CentOS Linux release 7.5.1804 (Core)