PI Alert Configuration to multiple recipients

Hi

     I have configured an alert using tcode ALRTCATDEF, made all configurations. In my fixed recipient list, I do have one user, and an e-mail address configured via SU01 and alert configuration works just fine.

     My problem is, I do want to send alerts to multiple recipients using one user. I created a distribution list using tcode SO23. And when i enter the distribution list to e-mail addresses tab in user, i am having a " Email adress DL_ALERT is invalid" error.  I tried to with DL_ALERT@company.com yet it did not work. I know i cannot enter my distribution list 'DL_ALERT' to fixed recipients, so i am stuck.

Is there any way to figure this out?

Thanks.

Faruk