Official Abuse Clauses.
from the terms of service and acceptable use policy
          ------------------------------------

Policy on Spamming Specifically:

We do not allow our users to send Spam.  Please report any Spam to abuse@yourfavorite.com.  We would appreciate if you would forward a copy of the entire message, including all headers, as an attachment, so we can identify the sender, and terminate their account.  We can only fully authenticate messages if we receive a copy of the entire message, including all headers.

We will attempt to collect damages and enforce these terms of service against any proven violator.

Clear Definition:

Spam is ANY unsolicited or unwanted message that arrives
via email. Period.

If the mail was requested, and this request can be produced 
by the sender, then all follow up messages that are 
sent must contain ALL of the following when they arrive:

1. Valid "from" address. This means the from address must 
be a working domain name that someone can 
write directly to should they want to. If the address
is valid when the message is sent and is then
shut down after the mail is sent, it is still considered
an invalid "from" address.

2. Valid "reply to" address. This is slightly different to the "from"
address, it is the address mail goes to if someone 
clicks reply on the email. It may be the same as the "from"
if you choose.

3. Valid sender information, including the name of the company
or individual that sent the message, a valid phone 
number, and a physical postal address where written 
correspondence can be sent if needed.

4. Valid remove processes must be in place to instantly remove
any individual from future mailings upon request. A 
real-time remove link or standard reply with "remove"
in the subject line are acceptable if they work every
time, without exception.

If all of these factors apply, and the mail is sent with the prior 
permission from the recipient, then the mail being sent is not 
considered spam.