No need to reinstall anything for this. Kaltura is compliant with all of the following:
CentOS 6.n, 7.n, Debian stable and testing and Ubuntu 14.04 LTS.
What do you see in /var/log/maillog? do you see attempt to send emails that failed?
Is your batch daemon running?
How about the kaltura logs under /opt/kaltura/log/batch/mailer*log?