Customer cannot signup on the portal if a deleted Atlassian Account with the same email previously existed

Summary

Customer cannot signup on the portal if a deleted Atlassian Account with the same email previously existed on the tenant.

Steps to Reproduce

1. create standard (non-portal, AtlassianID SSO) user with email user@blah.com
2. revoke access
3. remove user
4. attempt sign up as user via portal view with email user@blah.com
5. no portal account is actually created, the sign up email is never received by user despite UI saying it has sent.

Expected Results

User receives signup email to activate their account.

Actual Results

User doesn't receive signup email to activate their account.

Workaround

• Site admin can create the problematic customer accounts themselves via the public API https://developer.atlassian.com/cloud/jira/service-desk/rest/api-group-customer/. Then user can signup again.
• Problematic customer accounts can be added from the customers page in the project. Then user can signup again.
• Add problematic customer accounts back as Atlassian Accounts in admin.atlassian.com but revoke all their product access. Then user can login using their Atlassian account.