Hi @Robyn McLeod ,
Welcome to our forum!
If you are using shared mailbox or you and your husband both are using an email mailbox, if one of you makes a change to the mailbox, the other is bound to see the change in the mailbox.
If you and your husband want to manage their respective mailboxes separately, we recommend that you both use two separate mailboxes. Then you could create a group and add your mailboxes into the group. In this way, email sent to the group will be displayed in the respective Inbox of both of you. For more information about creating a group, please refer to: Create distribution groups - Microsoft 365 admin | Microsoft Learn.
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