To send spool list to multiple users while defining background job via trans. SM36, create a distribution list. This distribution list will contain the addresses of multiple users.
To create distribution list: Call transaction SO01 (SAP office: Inbox). Click on the Distribution Lists button on the tool bar and click Create Icon. Enter a name for your distribution list, say, Test_Grp and fill in other relevant details.
Click on the Distribution list content Tab and enter the addresses of multiple users. Check on the Express check box to send documents to the recipients as an express message.
Now while creating background job for your program via SM36, enter the distribution list name (Test_Grp) when you click the Spool list recipient button. This will enable the spool list to be sent to multiple users.