The following was forwarded to me yesterday.
>Dear Email List Manager;
>In the upcoming months, Yahoo! Mail will become more aggressive
>in its acceptance of SMTP connections and will begin denying
>connections by IP address when these connections do not conform
>to Internet standard practices. To continue uninterrupted
>access and prioritized delivery, you should ensure that your
>email address lists are well maintained. If you are conforming
>to these standards, then these changes should only affect
>you positively. We anticipate you will see improvements in
>delivery times and in available connections.
>If you want to ensure that your email is prioritized and
>your SMTP connections are not blocked, please:
> Reply to this email with:
> o Your current list of IP address(es) from which your
> mailings are sent.
> o The domain names of your "From" address(es)
> of your mailings.
> o Contact email address (will be used periodically to
> update your IP and From addresses).
> Remove email addresses that bounce.
> Bounces are an indication that the mail could not be delivered
> because the user does not exist, no longer exists, or is unable
> to accept your email. Well managed lists remove addresses
> that generate bounces. A particularly popular technique
> for managing bounces is to use VERP to identify the recipient
> address that has failed.
> Maintain accurate reverse DNS information
> for your mail servers. Yahoo! Mail makes extensive DNS checks
> for each connection and an accurate reverse DNS will ensure
> prompt processing of your connection and email.
> Pay attention to the responses from our SMTP servers.
> The SMTP protocol defines response codes that tell your
> server what to do next. In particular, our server will send
> "500" SMTP response codes to indicate problems
> that you need to investigate. For example, if you send email
> to too many recipients in one connection or to too many
> invalid recipients, our servers will respond with a "500"
> range SMTP code, indicating a permanent error.
> Don't send unsolicited email.
> Make sure that all email addresses are confirmed with an
> opt-in process that ensures the recipient wants to receive
> your list.
> Provide an unsubscribe email address in each mail you send.
>Thank you for your cooperation.
>The Yahoo! Mail Team