Can I destroy this orphan's letter?

As part of the Wintersday holiday, an orphan sends you a message in the mail which contains an item called [Orphan Laine's Letter]. It appears to just be taking up an inventory slot, but attempting to destroy it raises a confirmation dialog:

Is this safe to delete, or will it be needed further down the line?

2 Answers

It is exactly as your link describes it :

Orphan Laine's Letter is a letter that starts the Warming Grawnk's Heart scavenger hunt. When double-clicking, it will point towards your home instance.

It does nothing less, nothing more, start the scavenger hunt and feel free to do whatever you want with it after that !

It's for a scavenger quest, double clicking the letter should point you to your racial home, going here will start the quest. Unless you do want to do the mission destroying the letter should be fine.