How many invitations can be sent to a user?
A CRM user can be re-invited from one org account up to a maximum of seven times.
Sending invitations to users from different organization accounts
CRM users who are already part of a CRM account can be added and invited to multiple org accounts. They will be able to accept the invitation from another account without having to disassociate from your existing account. Read more about adding and inviting users.