Reputation Warming

Make sure that every email is wanted, relevant, personalized, and engaging. Obtain opt-in consent before sending a message, and include content that’s on brand and interesting to your subscribers. The more engagement that a message gets, the higher your sending reputation will likely be. MBPs may track opens, clicks, and view time and compare them to bounce and complaint rates to determine the quality of the sending reputation.

Authentication Guidance

Before you begin warming your IP or sending domain, make sure that your domain meets bulk sender guidelines enforced by major MBPs. Then, test that your emails follow DMARC, SPF, and DKIM authentication protocols through a service such as aboutmy.email.

We recommend sending to your most active and engaged subscribers during this critical period. MBPs use these initial sends to assess your sending reputation. The more opens and clicks your messages get, the quicker your sender reputation is established.

Reputation Scoring

The process of warming an IP address or domain is contingent on its reputation with MBPs. Your reputation score is based on the number of opens, clicks, bounces, and complaints an IP address or domain receives. A higher reputation influences how quickly you can increase your send volume.

To improve your reputation, make sure that you have a clear double-opt-in process and follow good list hygiene practices. Give subscribers a say in the kinds of content that they receive and how often they receive them. Remove unengaged subscribers from your mailing lists, and limit email sends to only those subscribers who have engaged in the last six months.

High bounce rates, especially hard bounces, hint at a low-quality mailing list. A high complaint rate signals that your subscribers don’t want your emails or think that the emails are spam. In general, aim to keep bounce rates under 2% and complaint rates under 0.1%. For more specific guidance, review the email sender guidelines for Gmail.

Increasing Send Volume

To build a strong sender reputation, gradually expand your audience based on email interactions. For your first week, slowly increase your send volume. Send emails to only your most engaged recipients, including new sign-ups and anyone who’s engaged in the past month.

After that, expand your sending list each week by one month of engagement. For example, during week two, send messages to anyone who’s engaged in the past two months. During week three, send messages to subscribers who have engaged in the past three months, and so on.

Starting during the sixth week, proactively remove unengaged recipients from your list. Don’t send messages to subscribers who haven’t engaged in over six months.

If at any point you notice a dip in performance, scale back your send volume to the last successful threshold to protect your sender reputation.

Volume Targets

Throughout the warming process, if engagement is low or your messages are hitting spam filters, limit daily volume increasing to 10-20% and remember to focus on only the most active subscribers. When you see high open rates and minimal issues, you can start to increase sending volume by 20-30% each day.

After you send a message to 60-70% of your total audience volume, you open up sending to everyone. This process usually takes senders four to seven weeks.

Maintaining Reputation

The goal of warming is to build your reputation and establish your typical traffic patterns with the MBPs and receivers. The key to ongoing success is to maintain that reputation and volume by consistently sending similar volumes to your subscriber base and not surprising them with unexpected content. If you stop sending for an extended period (for example, over one week), scale back your volume, then build back to your peak volumes. If you stop sending for three or more weeks, start your warming efforts over at day-one volumes. A significant reputation drop can take months to recover from.

Opt-In Consent

When a customer or subscriber gives opt-in consent, they tell you explicitly that they want to hear from your company or brand.

Acceptable forms of explicit consent look like contacts who:

• Submitted a form on your website
• Made a purchase with your brand in the last six months
• Entered a written contract with your brand in the last six months
• Donated to or volunteered with your company in the last six months
• Signed up for and are active users of your service, organization, or club
• Filled out a paper or electronic sign-up sheet specifically for your newsletter

Use a transparent and customer-driven opt-in process. Prechecking the opt-in box isn’t recommended and can cause complaints from subscribers and potentially register false addresses in your database.

To minimize complaints, set expectations at sign-up for how often you engage customers. To drive more sign-ups, you can even give customers the option to set a communication frequency preference.

Use CAPTCHA to prevent bot sign-ups. Bad actors can exploit forms and use your subscriber list to harm your company’s reputation.

Avoid Spam Traps

The most common types of spam traps are honeypots (addresses created specifically to catch spammers) and recycled spam traps (addresses that can be reused after 6-12 months of inactivity). Successful honeypots suggest issues with your opt-in process or that your list may contain purchased subscriber data. Successful recycled spam traps suggest list hygiene issues and that you should scale back your audience to subscribers with engagement in the last six months. Too many successful traps can cause blocklisting issues with specific receivers, or even listing at Spamhaus (a third-party data provider for some MBPs) that can cause widespread blocking issues.

You can generally avoid spam traps if you:

• Don’t purchase or rent lists.
• Actively remove hard bounces from your campaigns.
• Continuously re-engage your inactive subscribers. At three months of no engagement, a subscriber is considered uninterested and the odds of winning them back decrease greatly. Consider a highly targeted campaign designed to win back their business. If they still don’t engage, consider dropping them before the six-month window.
• Remove unengaged subscribers. After six months of no engagement, remove them from your mailing list.