[exim] relay not permitted when sending mail from a specific…

In my macbook i've added me@??? to mail client. it successfully connected to the imap dovecot server. however when i'm sending a mail from this mail account, I get the following error at my exim server:

Nov 29 15:29:02 RPi1B2 exim[14576]: 2019-11-29 20:59:02 H=([192.168.1.103]) [157.48.99.88] X=TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no F=<me@???> rejected RCPT <myfriend@???>: relay not permitted
Nov 29 15:29:02 RPi1B2 exim[14576]: 2019-11-29 20:59:02 H=([192.168.1.103]) [157.48.99.88] X=TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no F=<me@???> rejected RCPT <myfriend@???>: relay not permitted

... Necktwi