SUS - MM Scenario: notification mail not sent to all Supplier Users

Hi,

we're in a SUS-MM scenario and we publish Purchasing documents (PO and/or SAR) to SUS portal.

The notification mail for new published documents are sent only to the e-mail address of the Supplier (imported from SAP to SUS) which is in the SAP Supplier Master data. But if the Admin supplier creates other users for the supplier (F1 / F2 / F3), the notification mail for new published PO/SAR are not sent to the mail address of F1 / F2 / F3 users. Is it the standard behavior or is there some missing customizing setting missing?

Our customer wants that notification mail are sent to all the mail addresses of the Supplier Users.

Has someone had this kind of requirement? and, if it is not achievable via standard customizing, which could be the right solution to meet this requirement?

Thanks in advance