I have two Domain Controllers for one domain and need to transfer an smtp-address from one user to another. I deleted the mailaddress from the first and when trying to add it to the second user, I get the error Id c103412e7, "this Mailaddress already exists in your organisation". However, when searching for the mailaddress via the Advanced Search via LDAP-String "proxyAddresses=smtp:firstname.lastname@example.org", It doesn't show the address anymore. I tried manually synchronizing both domain controllers with each other, but did not have any luck.
Any ideas on why the mailaddress still seems to exist somewhere?