[exim] Open relay for a one account

Welcome in my first mail in exim-users

I must configure in my exim server one user account that server will be
open relay for this account. It means, that user from one of my domain,
that i serve, may send mail without a password. My server isnt currently
a open relay system, i need to configure only one account without a
prompting a password at sending email.

I suppouse, that i need to change one option in my acl configuration.
Can anybody suggest me which one is it?


Best regards!