To add non-member, non-owner senders to an L-Soft list you will want to first go to:

https://lists.upenn.edu

and login with your L-Soft account information. If you do not yet have an L-Soft account set a password to create one. Once logged in go to List Management>List Dashboard:

Scroll down to the bottom to see a list of lists to which you have administrative access, alternatively you can also search for a list by name. Once you have located the list you will want to click on Configure below the List Name to navigate to the List Configuration page. Clicking View under Subscribers will allow you to review current list membership.

Once in the List Configuration page you will then want to select the Access Control Tab:

Under Access Control scroll down to the Send key, under Send you will find the field Special:

Enter non-member, non-owner sender addresses in the Special field to allow them to be able to send to the list. You can also add other L-Soft lists to this field to grant sending permissions to either other list members - (OTHERLIST) or the owners of another list - Owner(OTHERLIST).

If you have any trouble please reach out to your LSP for assistance.