How can contacts get into reciepient cache that are not on my contacts list

I have contacts in the recipient cache that I know but are not in my contacts list.
They may have been on an email sent to me in the copy list.
Has anyone got an answer to this one please?
Where do they come from?

Hello Brian,

These contacts come from the recipient’s history and are saved in Menu > Tools > Settings > Mail > Compose > Recipient’s history.


thanksf or that but they were cc on an email sent to me does it store cc as well?