old email keeps popping up error

We have a member whose email was invalid so we changed to her gmail email.  I don't see the invalid one in any of the membership lists, but every email sent has a notice about her email.  Where can I delete it at?

Support email received
Your email message to This email address is being protected from spambots. You need JavaScript enabled to view it. could not be delivered
and was returned to the FreeToastHost server. Details are as follows:

        Recipient Email Address: This email address is being protected from spambots. You need JavaScript enabled to view it.
        Email Subject: [CPTMClub] Crofton Professional Toastmasters Club Meeting Agenda for
        Date Sent: Sat, 18 May 2024 12:52:14 +0000

        Diagnostic Code: 550 Host unknown
        Delivery Status: 5.1.2 hostunknown
        Date Last Attempted: Sat, 18 May 2024 12:52:15 GMT
Thanks
Craig

Look in the members secondary email in their profile.