Aren't ghosts funny? You forget about them for a while, and then suddenly you're feeling all happy and fuzzy in your favorite hat and... smack, you're face to face with them. You look them straight in the eye, to say 'I'm not scared of you anymore, ghost,' and then pretend you never even saw them. But they know you did. They can tell.
Ghosts have all sorts of ways of trying to wedge their way into your life. Little reminders of their presence, just to make sure you don't forget. A pointless email. A little trinket left behind.
What can you do? No matter how many things you delete or throw away, there always seems to be something else. And even if you do manage to rid yourself of reminders, there's the chance they'll just decide to show their faces.
All you can do, really, is keep moving. Wash your face. Remember that you're actually okay. Don't let the ghosts know you noticed. And then hopefully they get bored after a while and move on, themselves.