Question
What is the cpanelsolr process?
Answer
cpanelsolr is the software that manages the Dovecot text searches for both Roundcube and Horde. This was added in cPanel version 64.
https://docs.cpanel.net/release-notes/64-release-notes/#imap-full-text-search-indexing
Fast Email Searching (IMAP Full Text Search)
Full-Text Search Indexing (powered by Solr) provides fast search capabilities for IMAP mailboxes. Users of iOS devices, Microsoft® Outlook™, SquirrelMail, Horde, Roundcube, and Mozilla™ Thunderbird will notice significantly improved search speed and convenience.