It’s popular for many F2P live service games to use some sort of mail system so the devs can make announcements to be read in-game, attach gifts of in-game currency/items.
While I’m not necessarily suggesting Funcom give stuff away, the system could also be used by Admins to warn a player if they are in violation of a structure rule, for example, and give them a week to correct the issue, if possible, before taking action against them. Maybe in such case the warning mail could also have a button to alert Admins the player has corrected the issue and requests Admin review.
In any case, this is one example in which such an in-game mail system can facilitate communication and process between devs and playerbase.