When sending an invitation to another with Calendar, this message appears:

The e-mail account does not exist at the organization this message was sent
to. Check the e-mail address, or contact the recipient directly to find out
the correct address.

I have already renamed the person't *.nk2 and have manually deleted the name
when it appears in the address line. Does not work. I logged out and back
in.

I've looked at exchange legacyDN with ADSI edit also to the possible people
with this deleted user. I don't see this person on delegates or anything in
their Outlooks either.