• Use a consistent IP address to send bulk mail.
• Keep valid reverse DNS records for the IP address(es) from which you send mail, pointing to your domain.
• Use the same address in the 'From:' header on every bulk mail you send.

We also recommend publishing an SPF record, and signing with DomainKeys.

Each user on your distribution list should opt to receive messages from you in one of the following ways (opt-in):

• Through an email asking to subscribe to your list.
• By manually checking a box on a web form, or within a piece of software.

We also recommend that you verify each email address before subscribing them to your list.

The following methods of address collection are not considered 'opt-in' and are not recommended:

• Using an email address list purchased from a third-party.
• Setting a checkbox on a web form or within a piece of software to subscribe all users by default (requiring users to explicitly opt-out of mailings).
  

A user must be able to unsubscribe from your mailing list through one of the following means:

• A prominent link in the body of an email leading users to a page confirming his or her unsubscription (no input from the user, other than confirmation, should be required).
• By replying to your email with the word 'unsubscribe' in the body of the message.

• Automatically unsubscribe users whose addresses bounce multiple pieces of mail.
• Periodically send confirmation messages to users.
• Include each mailing list they are signed up for, and offer the opportunity to unsubscribe from those in which they are no longer interested.
• Provide a 'List-Unsubscribe' header which points to a web form where the user can unsubscribe easily from future mailings (Note: This is not a substitute method for unsubscribing).

It's possible that your users forward mail from other accounts, so we recommend that you:

• Explicitly indicate the email address subscribed to your list.
• Support a URL method of unsubscribing from your mailing list (this is beneficial if your mailing list manager can't tell who is unsubscribing based on the 'Reply-to:' address).
  

• All bulk messages you send must be formatted according to RFC 2822 SMTP standards and, if using HTML, w3.org standards.
• Messages should indicate that they are bulk mail, using the 'Precedence: bulk' header field.
• Attempts to hide the true sender of the message or the true landing page for any web links in the message may result in non-delivery.
• The subject of each message should be relevant to the body's content and not be misleading.
  

While Gmail works hard to deliver all legitimate mail to a user's inbox, it's possible that some legitimate messages may be marked as spam. Gmail does not accept 'whitelisting' requests from bulk senders, and we can't guarantee that all of your messages will bypass our spam filters. To make sure our users receive all the mail they'd like to, we've provided them with a method for sending us feedback about messages flagged as spam -- users have the option of clicking a 'Not spam' button for each message flagged by our spam filters. We listen to users' reports, and correct problems in order to provide them with the best user experience. As long as our users don't consider your mail as spam, you shouldn't have inbox delivery problems.

If you send both promotional mail and transactional mail relating to your organization, we recommend separating mail by purpose as much as possible. You can do this by:

• Using separate email addresses for each function.
• Sending mail from different domains and/or IP addresses for each function.

By using these tips, it's more likely that the important transactional mail will be delivered to a user's inbox. Our guidelines are meant to help you build a good reputation within the Gmail system, resulting in continual delivery to Gmail inboxes.

If others use your service to send mail (for example: ISPs), you are responsible for monitoring your users and/or clients' behavior.  

• You must have an email address available for users and/or clients to report abuse (abuse@yourdomain.com).
• You must maintain up-to-date contact information in your WHOIS record, and on abuse.net.
• You must terminate, in a timely fashion, all users and/or clients who use your service to send spam mail.