Outlook marks sent emails as not read when applying a move rule

Question

I have a customer with multiple imap and pop email accounts but he wants to have all the sent messages collected in a single folder.
So I decided to deactivate the "save sent emails" in options in Outlook 2019 and added new rules (one for each account) that move a copy of the sent email in the chosen "Sent" folder.
What is very disappointing is that in this manner all the sent emails are now marked as "to be read", adding the unread count number beside the "Sent" folder.
Why this very weird behaviour and how to avoid it?

Answer 1

The problem can be solved with VBA as described here:
https://www.slipstick.com/outlook/rules/mark-items-read/