STANDARD:

An electronic message is "spam" IF: (1) the recipient's personal identity and context are irrelevant because the message is equally applicable to many other potential recipients; AND (2) the recipient has not verifiably granted deliberate, explicit, and still-revocable permission for it to be sent; AND (3) the transmission and reception of the message appears to the recipient to give a disproportionate benefit to the sender.


DISCUSSION:

(i) Trivial or mechanised personalization such as "Dear Mr. Jones, we see that you are the holder of the JONES.COM domain" does not make the personal identity of the recipient relevant in any way.

(ii) Failing to click the "do not send me marketing literature by e-mail" button in a web sign-up form does not convey explicit permission. Only when the default result is "no followup e-mail" AND the inbox impact is clearly stated before any action which changes this result, can permission of this kind be conveyed.

(iii) The appearance of disproportionate benefit to the sender, and the relevancy of the recipient's specific personal identity, are authoritatively determined by the recipient, and is not subject to argument or reinterpretation by the sender.

(iv) Non-personal e-mail always places a disproportionate cost burden on the recipient, and is considered to disproportionately benefit the sender unless it was verifiably solicited or by the
recipient's willing exception.

(v) A message need not be offensive or commercial in order to fit the definition of "spam." Content is irrelevent except to the extent necessary to determine personal applicability, consent, and benefit.

http://www.mail-abuse.org/standard.html