With the ignore feature, you can ignore certain players who are on your ignore list. Public messages of these players do not become readible to you and players on your ignore list may not send private messages to you.
Safe Deletion
Safe Deletion is when you delete a private message, so it does not become visible to you, but the person who send it and a moderator can still see the message.
Full Deletion
Full Deletion is when both the sender and the receiver have deleted the message. This message is really deleted.
Storage
All messages are stored until fully deleted.
Date & Time
The game time is used to order messages.
Message Size
The size of a message is limited to 65,536 characters, that includes spaces.