i am unable to verify my hostname certificate in my mac while trying to login
You are probably trying to login using IP. If you know your server’s domain name, use it instead. If your domain name is not resolvable in the network, then in Spark go to Advanced and put IP into Host field (but still use domain in the Domain field).
I don’t know if this is still a problem or not for this person, but on version 2.8.3 of the Spark client for Mac, I get an “Unable to verify certificate” error when trying to log in on a newly built Openfire Server version 4.2.3 on Windows connected through Active Directory, with an authentic wildcard certificate purchased from an external certificate authority for my domain. I have also imported the GoDaddy’s certificates into the trust store.
Nevermind, I was able to track this problem down finally. Please see post https://discourse.igniterealtime.org/t/spark-2-8-and-newer-unable-to-verify-certificate/42088/10