Please follow custom routing settings and restore them when users are removed and readded

[jessehouwing]

As Administrator for some orgs I try to stay a member or even remove myself from organizations under the enterprise's control to reduce any attack surface when I'm not in the capacity of an admin.

These organizations require notifications to be sent to enterprise verified domains.

When I remove a user (including myself) from an organization, an email is sent to my primary notification email, but not to the configured custom route.

In this case the email is sent to gmail, not our office365:

When I add a user back to an organization, their custom route isn't restored and emails are again routed to their primary notification email. Or, for the organizations under our enterprise they don't get any email until they reconfigure their custom route.

Ideally GitHub would use teh custom route to send the "user was removed" notice. I can understand possibly sending a copy to the primary notification address.

Ideally GitHub would restore the custom route along with the restored team memberships and repository access.

Ideally GitHub would ask to select the notification to setup the custom route when a user accepts the organization invitation.