Well, I thought this would refer to a different kind of alert that I believe could really improve player retention: character event alerts. Pick some: participated in battle, received a duel challenge or a unique item offer, liege paused/quit, new referendum to vote in, new knight joined your region, maybe even "got letter from your /council member, liege, council member from other realms/" or "you have 13 unread letters from your realm, one of them is a private letter" (after a few days of not logging in", "realm X has declared war on your realm", stuff like that.
Does it make sense? I liked how Might and Fealty kept sending me reminders about my chars.