Following upgrade to TB 45.3.0, I see that the Correspondents column of the Advanced Search (Ctrl-Shift-F) results pane has been replaced with the From column, at least when mailnews.ui.upgrade.correspondents preference set to false in the Config Editor and the new mail.threadpane.use_correspondents preference remains at its default of false.

But I was surprised that the Recipient column does not also appear with the From column when the Correspondents column is suppressed, as happens with folder columns. Even after I add the Recipient column to the Advanced Search pane display, it does not remain when I later view that pane. I was advised on the thread for Bug 1277844 that "We restored the original behavior [for the Advanced Search pane] of TB 38 which only showed the From column." I believe that it is reasonable to expect that the columns a user selects for the Advanced Search pane should remain in place from view to view as do the column selections for folders. Please consider adding that functionality in a future release.