Which email addresses are available to edit when Managing Email Addresses?
Only fields that have a date type of Email are available for selection on the Manage Email Address page.
Ensure users have Edit Field Level Security (FLS) permissions to the email type fields, the field is on the users page layout as Editable and are not included in the APPROVED_EMAIL_FIELD_EXCLUSIONS Approved Email Settings.
Email fields from Addresses that are marked as Inactive = Yes are not displayed.
CRM Help Documentation: Managing Approved Email Recipients