FWD and FW are both spelling forward and are interchangeably used in emails. The variation largely becomes dependent on the email service or personal choice. There are also platforms that automatically use FW and those ones that use FWD. In any case, these are the signs that the message is being relayed to another sender. The translation does not change the meaning and both versions are typically easily comprehended by recipients regardless of whether it is in a professional or casual context.