If you accidentally sell something you didn't mean to, you can use the vendor Buy Back tab to recover the item without any more cost than what it was sold to you for.
But what can you do if you accidentally delete a mail from your mailbox? One that has items or credits in it? The "Delete all checked messages" and "Get all checked message attachments" are right next to each other in the interface, which similar sizes and icon emphasis, so it can be easily mistaken.
Is there any way to get back a deleted message, or at least the items/credits in one?