FYI – For Your Information. It replies that no reply is needed, and is usually a short message.
Example: "FYI Free Donuts in the Kitchen".
URGENT – Used for when something is really urgent. Don’t use it if something is not urgent. And if something is truly, truly urgent, it’s best to follow up with a call or IM as well.
Example: "URGENT: Final reminder to file quarterly team reports"
EOM – End of Message. This is usually used when the entire email is in the subject line.
Example: Elevator is broken today, please use stairs EOM
NRN – No Reply Needed. Indicates that the receiver doesn’t need to reply. There is likely a body to the message but no response is needed.
Example: "Jennifer wants you to call her back NRN"
NFA – No Further Action. Same as combination of FYI and NRN. For your notification only, no action or reply needed.
Example: "Mr. Tanaka will be in at 11am not 10am NFA"