Email notification not send while sharing contract to supplier portal

Summary:

We have updated the profile 'ORA_OKC_SHARE_EMAIL_REPLY' (Reply Email for Share Notifications) with an internal email id to send the notifications to supplier.

But while sharing the contract with the supplier contact using the 'Share in Supplier Portal' action, the supplier contacts are NOT receiving the email notification saying that the contract has been shared with them. Only the In-App worklist notification is received by the supplier contact. Similarly when the supplier sends a notification from the supplier portal, the contract owner also does not receive the notification in email.

Also in the mailbox used in this profile 'notificationserpcloud@xxxxxxx.com' there is an 'Email Delivery Failed' message received.