If the email address is absent from the Public Distribution List (PDL) configuration, it is not possible to use a PDL in Cisco Unity 4.x.
When the issue occurs, this error message appears:
This recipient's e-mail address does not exist. If this recipient is new, wait a few minutes and try again
Complete these steps in order to make sure the distribution list has an email address:
From Active Directory Users and Computers, search for the distribution list, right-click it, and choose Properties. Verify that there is a Simple Mail Transfer Protocol (SMTP) address.
Choose Enterprise Manager > Databases > UnityDB. Select the distribution list table, right-click it, and choose open table > return all rows. Verify that the distribution list has an email address in the SMTPAddress field.
If not, choose Start > Programs > Microsoft Exchange > System Manager. Expand Recipients, and click the Recipient Update Service (RUS) folder in the right pane. Different instances of the RUS service appear. Right-click each instance, and choose Update Now.
Return to the distribution list table. If it is still open, close and reopen it. See if the e-mail address is populated.
If not, it is possible to hardcode the email address manually on the SQL table.