[exim] Domain of sender address does not exist

Dear all,

I'm using Exim 4.34 on Linux, and configured to have
different subdomain: sub1.mycompany.com
sub2.mycompany.com.
When I send from user@??? to some address I received this
error message:
553 5.1.8 <user@???>... Domain of sender address
user@??? does not
exist.

This is OK when sending from user@???.
The mail server have the FQDN: mail.mycompany.com
and DNS configuration is
mycompany.com MX 10 mail.mycompany.com
sub1.mycompany.com MX 10 mail.mycompany.com
sub2.mycompany.com MX 10 mail.mycompany.com

Is there anything I have to do with Exim configuration to fix this problem.

Thanks for your time.

Nguyen Duy Tho