We recently got a feature request to implement a CC column in the table view. Looking through Bugzilla, we found a few bugs in this field:
https://bugzilla.mozilla.org/show_bug.cgi?id=522886 (from 2009) - implement "Recipients" column that shows all recipients (To, CC, and BCC)
https://bugzilla.mozilla.org/show_bug.cgi?id=522885 - Wrong label: "Recipient" column must be labeled "To" as it doesn't show all recipients (missing headers: CC, BCC)
https://bugzilla.mozilla.org/show_bug.cgi?id=699588 - Message list: Implement missing (optional) columns for CC and BCC recipients (currently only column for TO recipients exists)
The Full Address Column add-on doesn't add a CC column, and the ColumnsWizard add-on has long been abandoned.
Please get in touch if you would like this feature to be implemented and if you want to pledge some funding.