Archiving/storing sent messages

I store all messages that I send out. The normal Sent folder under each mail account keeps them only for the day.
I have created my own SENT folder an a rule to copy all sent messages into it. Over the years it is a massive folder, but worth it.
But this folder behaves differently from the normal Sent folders.
In the Preview column, it does not show the recipient name or address, it shows the sender’s address, which in all cases is my own.
When I look for an old email that I send to someone, it is difficult and time consuming, because I have to open and close many messages before I find the right one.

Would it be possible to show the name or address where the message was send to?

Or, is there another way how to archive all sent messages? The included archiving feature does not give the option of archiving the Sent folder on its own, and I don’t want to archive everything.

Thanks