As an admin I would like option to re-send an invitation email to a customer

Summary

When a customer already exists in a Service Desk, if I re-invite them using an email address, nothing happens. It will be silently ignored.

Steps to Reproduce

1. Go to the 'Customers' page in a Service Desk
2. Invite a customer, by clicking 'Invite', enter an email and click 'Send invites'
   • The invite will be sent
3. Do the same process again with the same email address

Expected Results

Either:

• a new invite email is send (if this process was done twice, is most likely because the first one didn't work) or warn the user that a customer with that email already exists and no email will be sent.
• No invite is sent, but I receive a message informing me this user is already a customer, but would I like to resend the invitation to this Service Desk

Notes

The initial invitation containing the link to set a password will only ever be sent once, when the user is initially created. After this time, the Forgot password link can be used. Invitations to different Service Desks send a new invite email each time, and these are what can be re-sent.