FYI
I have been getting spam for Yahoo people so I sent a email to
them(support@yahoo.com) and they replied with the following.

Tom

Thank you very much for reporting this incident to Yahoo!.  Mass
distribution of unsolicited email messages, or spamming, violates the
Yahoo! Terms of Service (TOS).

We have taken a number of measures to discourage spamming, such as
limiting the number of messages that can be sent from a single account
in one day.  In this particular case, we have identified the account
used to send the unwanted email message, and have taken the appropriate
action as per our TOS.

Thank you for working with us to keep Yahoo! a friendly email
environment.  We take the operation of Yahoo! Mail very seriously.  In
the future, if you receive an unwanted email message that appears to
originate from a Yahoo! Mail account, please forward the message with
full headers directly to us at abuse@yahoo.com.

Thank you,
Yahoo! Customer Care