Related Clues:

• Letters that can't be found at the post office
• It's sent with a click
• Quick correspondence
• Recording medium
• Message by modem
• Potential virus carrier
• Online letter
• Type of tape
• Letters that lack stamps
• Cyberspace epistle
• USPS alternative
• It may arrive with attachments
• Cybernote
• It could have a virus
• Net receipts?