How can I configure exim4 to send emails to my own domain outside of the server?

Question

Exim

DNS registered all addresses on the VPS, with the exception of mail stmp pop mail, which go to the hosting
i.e. the mailbox itself is rotated through hosting
on the server set exim4, the task was to make feedback on the site, but all letters outgoing from my domain to mine do not reach, but to another domain, for example mailru go normally, and for some reason letters are sent from www-data
tell me where to dig?