googling, at last i found them, there are named:
Code:
Unified Communications Certificates (UCC)
but no zimbra tech told us as you can install them,
see this post
they borned for exchange, hopefully they can be used with zimbra; i have your same issue with a customer of mine, they stated with domain.it and decided to chenge all to domain.com
now they are neither meat neither fish
any advise by zimbra's tech people on UCC will be very apreciated