Best Practices for Sending Emails to Multiple Recipients

Our Commitment to Deliverability

Rackspace is dedicated to protecting our network and ensuring your emails reach the inbox. Our Anti-Abuse and Acceptable Use teams work diligently to maintain the best possible reputation with mail providers. By following these best practices, you partner with us to ensure high deliverability for everyone.### Use a Bulk Email Service (Like Mailchimp)

Rackspace Email does not offer bulk email services. To ensure your bulk emails are not blocked, you must use a reputable third-party bulk email service provider (ESP) to send out your content. Reputable ESPs deliver your bulk email in a way that mail providers accept as legitimate mail and handle much of the technical compliance for you.

• Marketing, Advertising, or Promotional Emails: Use services like Mailchimp or Marketo.
• Transactional Emails (e.g., password resets, order confirmations): Use services likeMailgun or SendGrid.

For more information on prerequisite terminology, see Rackspace Email Support Terminology.

1. Critical Technical Best Practice: Sender Authentication (Mandatory)

Modern email ecosystems require cryptographic proof that an email legitimately came from your domain. For any organization sending over 5,000 emails per day, implementing DMARC, SPF, and DKIM is mandatory.

2. Recipients and List Hygiene

The quality and engagement of your recipient list are primary factors in determining your sender reputation.

List Accuracy and Spam Traps

• Ensure lists are current and accurate. Sending emails to a large number of invalid recipients (hard bounces) is a clear indicator of a poor list quality, which negatively affects your sender reputation.
• Avoid Spam Traps. Mail providers and ISPs use common invalid or aged email addresses as spam traps. Sending mail to these traps will result in immediate blocklisting of your domain. Use a validation service regularly.

Bounce Messages: Hard vs. Soft Bounces

When an email cannot be delivered, the receiving server sends a bounce message (or Non-Delivery Report/NDR) with a code indicating the reason. Understanding these types is crucial for list management:

• Hard Bounce (Permanent Error): Indicates a permanent delivery failure (e.g., the email address does not exist or the domain is misspelled). Addresses resulting in a hard bounce must be immediately and permanently removed from your list.
• Soft Bounce (Temporary Error): Indicates a temporary issue (e.g., the recipient's mailbox is full, the server is temporarily down, or the message is too large). Soft bounces may resolve themselves, but repeated soft bounces often signal a need to remove the recipient.

If you received a bounce message when sending an email, see our list of common email bounce messages for more information.

Confirmed Opt-In (Permission)

• Use confirmed opt-in practices when collecting email addresses for mailing lists. This means the user signs up and then clicks a confirmation link in a follow-up email. This greatly reduces the chances of your email being reported as unsolicited.

Engagement and Sunset Policy

• Prioritize Engagement: Mailbox providers track how recipients interact with your emails (opens, clicks, replies). Low engagement rates signal to ISPs that your mail is unwanted, even if it’s not marked as spam.
• Implement a Sunset Policy: Periodically identify and remove or stop mailing subscribers who have not engaged (opened or clicked) with an email in the last 6 to 12 months. These inactive users contribute to low engagement rates and damage your reputation.

3. Unsubscribe Compliance (Critical)

Allowing recipients to easily and immediately unsubscribe is mandatory and prevents users from hitting the "Spam" button instead.

• Provide an Unsubscribe Link: You are legally required to provide a clear, visible link in every marketing or newsletter email that allows recipients to remove themselves from your mailing list.
• Mandatory One-Click Unsubscribe: Implement the List-Unsubscribe header in the email's metadata. This enables recipients to unsubscribe with a single click directly from the email client interface (e.g., a banner in Gmail or Outlook), fulfilling a core 2024 compliance requirement.

4. Reputation and Platform Management

Your sending infrastructure requires a dedicated strategy to protect your reputation.

Website Reputation

• Maintain a safe and reputable business website that includes easy access to any privacy policies and clear contact information. Spam filter providers often audit high-volume senders by visiting their websites.
• Vet Partners: If you allow other companies to include references to your business in their emails, ensure they are reputable. If they send out spam, your domain could be flagged as being related to that abuse.

**Dedicated Subdomains and IP Warming

• Isolate Sending Traffic with Subdomains: Use different subdomains to separate critical transactional mail from bulk marketing mail.
  • Example: Use trans.yourdomain.com for password resets and receipts, and marketing.yourdomain.com for newsletters and promotions. This ensures that if a bulk marketing blast encounters a reputation issue, your critical transactional mail remains unaffected.
• Implement an IP Warming Protocol: If you are a high-volume sender using a new, dedicated IP address, you must follow a slow, deliberate IP warming schedule. This means starting with a low daily volume and gradually increasing the send rate over several weeks to build a positive reputation with ISPs.

5. Message Content

We recommend that you follow our person-to-person best practices when creating message content. Avoid using excessive use of spam triggers such as all-caps, excessive exclamation marks, or misleading subject lines.

References

• Rackspace Acceptable Use Policy, specifically the Mail Requirements section
• Rackspace Email Mail Terms
• Common Email Bounce Messages