Forwarded email header

• "Here's something interesting," in brief
• "Here are the relevant facts ...": Abbr
• "Just so you know," on a memo
• Heads-up letters
• Memo abbreviation
• 'By the way,' on memos
• Memo heading, maybe
• "Just a heads-up..."
• 'By the way' memo abbr

Wikipedia Word definitions in Wikipedia
FYI is a common abbreviation of " for your information ". "FYI" is commonly used in e-mail, instant as on messaging or memo and messages, typically in the message subject, to flag the message as an informational message, with the intent to communicate to ...