[otrs] customer can't see their ticket when sending emails to the otrs mail adress

hy all, i have a strange issue on OTRS, let me explain, i have customers which send email to an adress which is redirected to otrs. i can see the email in the OTRS agent interface the from in the email address is the same of the customer account but when i try to log on the customer interface with the username and password of the customer , i can't see tickets that have been created when he sends email to the OTRS system. anyone have a clue ? Rachid