Is it possible to set up an email address on my non-Plesk shared hosting email server to forward to more than one email address?

Yes, it is possible to add multiple forwards for the same email address. To do so:

• First, add one of the forwards as usual.
• Then go back to the main menu and click the Forwards link.
• Click the Modify button next to the notifications@domain.com forward.
• In the Destination field, you can enter an additional forwarding address.
• Finally, click Add. You should then see both of them shown in the list at the top.

Repeat this process to add additional forwards as needed.