How to identify if E-mail approval notification is sent to the approver?

Summary:

Business user has mentioned that they have not received E-mail for PO approval, but can see the approval in the application bell icon and able to approve the PO. This used to work before for the user. We have verified all the worklist setups and user preferences are correct. Other users are receiving the E-mails and able to take action.

Only one specific user has raised the issue and this user is receiving other types of E-mail notifications like requisition approval, fyi notifications etc. Only PO approval notifications are not received.

We also verified outlook settings if there were any Auto sweep rules/ if the E-mails were going to spam, no issues found here.