Don't print icon Delete after icon Keep internal icon Please share icon Keep secret
Below is our set of draft Privicons and a short explanation. Privicons are based on ascii and work somewhat similar to emoticons:-). We post this to stimulate further discussion. This is work in progress, and we'd love your input.

[-] - Don't attribute (Anonymous)

Don't Attribute (Keep Author Anonymous): The "Don’t Attribute" Privicon asks the recipient neither to attribute the e-mail to the sender nor to refer to the sender in any way associated with the e-mail’s content or status. However, unlike when the sender has used the “Keep Secret” Privicon, the recipient may freely quote, follow up, paraphrase, and otherwise make use of the original e-mail's content. (This is similar to the Chatham House Rule for meetings.)

[=] - Delete after reading/X days

Delete after Reading = [Within X Days]: The "Delete after Reading" Privicon requests that the e-mail’s recipient delete the sender’s e-mail either immediately or within a specified number of days. The Privicon may be represented in two different ways: 

1) [=] Delete after reading; 
2) [=X] Delete after X days.

[/] - Don't print
Don't Print: The "Don't Print" Privicon asks the recipient not to print the received e-mail. Some senders already do this for environmental reasons. In the privacy context, however, this Privicon means that the e-mail’s sender does not want to risk his e-mail being left at a public printer or otherwise floating around the physical world.

[o] - Keep internal

Keep Internal: The "Keep Internal" Privicon restricts the recipient's permission to share the e-mail – either by using its content or by forwarding the e-mail itself – to a group of friends, acquaintances, coworkers, etc common to both the sender(s) and the recipient(s). The judgment of whether a person is within such a circle belongs solely to the recipient, unless the sender chooses to clarify which group is acceptable. Essentially, the "Keep Internal" Privicon indicates that recipients should think carefully about to whom they might forward an e-mail, and that the sender does not want the message to be forwarded arbitrarily.

[>] - Please share

Please Share: The "Please Share" Privicon asks the recipient to share the sender's e-mail with anyone of her choosing. It represents an open invitation or license for the recipient to redistribute the e-mail. This Privicon may be supplemented by further instructions that clarify the e-mail’s copyright status: for example, the sender might also attach a Creative Commons license to her e-mail that allows copying and redistribution with attribution.

[X] - Keep private
Keep private: Sometimes we want to share information with someone while keeping that information secret from everyone else. The "Keep private" Privicon asks the recipient not to reveal anything about the e-mail, including information about its sender and its content. To strengthen this request, the sender might also attach another Privicon like  "[/] - Don't Print" or a "[=] - Delete after Reading/Within X days."