[Users] for some reason the sent messages are not filtered

[Ralf Mardorf]

On Tue, 6 Jun 2017 12:45:12 +0530, Jim Pachowski wrote:
>Option 1: If you're sending mail from the folder you want the mail to
>be stored in, in folder preferences, choose "Save copy of outgoing
>messages to this folder instead of Sent"

Since the OP mentioned that the incoming mails are filtered, at least
for replies the appropriate folder would be automatically selected.

>Option 2: Set up same filters as "Processing rules" to the Sent folder.

>Option 3: Option 1 + Option 2. ;)

Option 4: Use an individual email account instead of filters and
workarounds for outgoing messages and check

Configuration > Edit Accounts > Select an Account > Advanced >
[x] Put sent message in /path/to/