They need the ability to encode the message header---the recipient's address---in a new and detectable way.

ENGADGET: New 'subconscious mode' could improve smartphone battery life, supress your WiFi id

As Apple is using the reply-to address of a message's User Data Header to identify the origin rather than the raw source, receiving iPhone owners risk being fooled by a phishing attack (or just a dishonest acquaintance) that poses as a contact or a company.

ENGADGET: iPhone reportedly vulnerable to text message spoofing flaw

Melissa messages come with a subject header that starts "Important Message From, " followed by a name.

CNN: How to protect yourself against Melissa