so do you email yourself messages/conversations you want to keep?

Also unless everyone use gpg, email isn't very secure nor confidential.

I tend to use notes on my smartphone for information I want to keep that are encrypted and synchronized on my desktop when reaching home. Having said that I often forget to copy a message to a note because it is a manual process and it is sometimes not trivial to anticipate that an info will be important enough in the future that you need it again.