What is an Email Sending Reputation and How Can You Improve It?

The concept of establishing reputation as a sender isn’t new to email marketing. For years you’ve heard how important it is to “warm” your sending IPs in order to establish how the mailbox providers interpret their users’ interaction with your mail, which ultimately dictates inbox or spam folder placement. There have even been reputation monitoring solutions that provide a numerical “score” value for senders based on factors ranging from volume, to number of bounces to spam trap hits.

The reality is, email sending reputation is complex, and there are multiple factors that go into building it. Your choice of Email Service Provider (ESP) isn’t going to dictate whether or not you reach the inbox of your subscribers, but factors such as ensuring you obtain clearly outlined opt-in, sending relevant content that drives value, and following list hygiene best practices all play a huge factor.

Below we’ll dive deeper into the groundwork for building a strong sending reputation from the start, discuss the benefits for companies to establish those habits early and revisit them often, and cover a few suggestions for companies that may need a reputation reset.

What are the historical components of a solid sending reputation?

In 2024 the major mailbox providers (Gmail, Yahoo, Apple, Microsoft, Orange) started to come together to announce enforcement of a number of standards that had long been considered best practices. These Sender Guidelines laid out requirements for domain authentication standards (SPF, DKIM & DMARC) while also outlining agreed-upon spam complaint rates (0.10%) and requiring list-unsubscribe headers be included in all commercial communications. 

While these requirements weren’t necessarily new, they signaled a shift in the email industry that mailbox providers were starting to take protecting the inbox of their users more seriously and for marketers, that meant having a positive sending reputation with those mailbox providers was more important than ever before.

Wherever you send your marketing email from, the first thing you’ll want to do is ensure you have the infrastructure in place to meet your campaign goals. Do you send 1,000 emails each month from a single brand? Your solution is going to look different than someone sending 1 million emails every day across seven brands.

Each ESP may offer slightly different solutions here, but regardless of your sending solution, you’re going to want to ensure you authenticate any and all sending domains that will be used with SPF, DKIM and DMARC authentication (not sure what those are, you can read more here). 

Once you’ve authenticated your sending domains, you will want to ensure you have the IP sending capacity for your desired volume. Again, this may vary by ESP, but most will offer either shared IP access for lower volume senders or dedicated IP(s) for high volume senders. Dedicated IP(s) give a sender more control over their reputation and ability to reach the inbox, for marketers serious about inbox delivery, we’d recommend the dedicated IP path.

That’s not to say success with shared IP sending isn’t possible – it simply takes away one element of control over reputation from the sender. As long as your platform has controls in place to monitor their shared IP pool for potential “bad actors” and can add/remove IPs as needed, you should be just fine.

This is the point where you’ve traditionally been told to start “warming” your IPs, a process that involves introducing low volumes of mail in a repetitive manner in order to allow the mailbox providers to start gathering data points and determine your “reputation” as a sender.

The problem is, there’s more to reputation than just the IP(s) being used to send mail. Much like the Sender Guidelines mentioned above, mailbox providers have adapted their algorithms over time and as they’ve become more sophisticated, the concept of reputation has expanded to include factors such as domain history, subscriber engagement behavior and relevance of the content being sent.

The new look of sending reputation

To clarify, authenticated domains and sending IP(s) are still important to the concept of reputation. However, it starts even earlier than that. A company’s opt-in process and the amount of transparency/control it affords to its subscriber sets the tone for sending reputation well before that first email is ever sent. As mailbox providers make the shift to prioritize the user inbox experience, they want to know that a sender is acting in good faith.

Practices like obscuring a pre-checked opt-in box somewhere hidden in terms & conditions, for example, is a method of obtaining opt-in, that ultimately results in a high number of spam complaints or unsubscribes and low engagement rates.

On the other hand, presenting an optional opt-in to your customer that allows them to control not only what type of content they receive from you but also dictate how often your company engages them and through what channels, is likely to draw higher engagement from the subscriber and prevent negative reputation metrics like spam complaints.

Once you’ve got a transparent opt-in process in place, it’s time to think about your content. The days of batch and blast are behind us, and subscribers expect more from the brands they allow into their inbox. Content should be highly personalized and relevant to each unique subscriber: your product should solve a problem or offer a value add.

Remember, the customer who just bought your product doesn’t need a 15% off coupon for that same product – they need to know that you value the trust they’ve put in your company, so show them how your product is going to save them time in their day, offer testimonials from other customers, invite them to engage through social channels. Keep the conversation going, but keep it relevant, and you’ll make customers for life and most important, create brand advocates.

Look into additional solutions like BIMI and Apple Branded Mail, that can connect “reputation” to “brand visibility” (displaying your logo in the inbox), which acts as a visual reward for your good reputation. It can also help build trust with your subscribers and may improve overall engagement rates as much as 10% or more.

It’s essential  for marketers to understand this new landscape. For example, Gmail’s Promotions tab (the inbox for commercial mail) now uses machine learning to decide the relevance of emails based on a subscriber’s past engagement (opens, clicks, replies, etc.).

Emails that have a higher interaction frequency are prioritized and appear higher in the inbox which means if you are sending content the subscriber doesn’t deem relevant, odds are high they may never see your sends. This is likely to drive down open rates which negatively impacts your overall sending reputation.

Sending reputation is a lifecycle

From transparent opt-in, to ensuring you have the infrastructure in place to support your goals, to crafting the perfect campaign that keeps subscribers engaged (and your mail landing in the inbox), sending reputation is about more than just “warming” up to the mailbox providers. It’s about building that ongoing conversation in a manner that invites the subscriber to take some control of the relationship and really establish trust with your brand.

Yes, there are still some core components to establishing and maintaining a great sending reputation. Make sure your mail is:

• wanted [clear opt-in obtained]
• relevant [content is on brand/point to what the subscriber expects to see]
• personalized [batch and blast methods no longer drive the type of engagement needed to succeed in email marketing]
• engaging [opens, clicks and in some cases even length of time viewed are being tracked and compared to bounce and complaint rates to determine quality of the sender’s reputation]

But to be clear, this isn’t a one and done process. Building reputation is no longer as simple as “4-8 weeks of warming”. It starts well before your first email ever gets sent and continues to the inbox where subscriber engagement dictates your long-term success.

The mailbox providers are starting to come closer to an agreement on acceptable bounce and complaint rates for senders, since Gmail tends to be the largest percentage of most marketer’s subscriber bases, we recommend targeting their guidelines:

• Bounce rates < 2%
• Complaint rates < 0.1%

High bounce rates, especially hard bounces (which tend to indicate a permanent issue with that subscriber address), signal to mailbox providers that you have a poor quality list, which harms your sender reputation. Likewise, a high complaint rate signals that your emails are not wanted or considered to be spam which can be most harmful to your reputation.

Ongoing monitoring of your sending reputation is crucial for long-term success, and it can be as simple as reviewing your tracking for excessive bounce or complaints beyond those guidelines mentioned above. Other key metrics to watch are open and click rates.

While much has been made of the potential inaccuracies of opens and clicks due to mailbox filters such as Apple’s MPP, these rates still help us see the bigger picture of reputation performance. A decrease in opens can suggest potential bulking/blocking issues, subscriber fatigue, or a need to review your content for relevance and a clear call to action. A spike in opens might suggest an influx of new signups to your brand, that a campaign or content resonated well with your audience, or that there were bulking/blocking issues that have recently been resolved.

Use the data available to you to make sure your campaigns are performing in the published “acceptable” ranges of the mailbox providers and you’re much more likely to find your mail continuing to reach the inbox.

Can sending reputation be reset?

It’s never too late to get things right. Sending reputation continues to be tracked on a rolling basis by mailbox providers. This means that even the worst of senders can see the light at the end of the tunnel if they implement the practices shared above.

If your opt-in process could use a refresh, there’s no time like now to change, and while email is great for most marketing efforts, there are so many more channels subscribers may want to engage your brand through. Consider running a “re-opt-in” or “permission pass” campaign.Our partners over at Litmus share some examples of this strategy in this blog.

Once you have a refreshed subscriber list, take a look at your content for relevance and look for ways to personalize beyond that standard 15% off deal email. Remember, low engagement rates could mean your mail isn’t even being seen. Tell a story, offer a value add and continue to build your brand relationship.

Review your infrastructure setup, confirm any and all domains you use to send mail from are fully authenticated. There are free tools that can help with this if you aren’t sure how to read email headers. Check the health of your sending IP(s), create some test inboxes across various mailbox providers, if you can’t get mail to your inbox, it’s likely not reaching your subscriber’s inbox either.

More free tools marketers can use to monitor their reputation include Google’s Postmaster Tools and SNDS from Microsoft, both offer insights specific to their platform, but can be used to piece together the bigger picture of sender reputation.

Finally, consider scaling back volume. Many marketers get in a pattern of sending to their entire list to maximize ROI, but remember, the mailbox providers are starting to track that behavior and even expose it to their users by showing them just how many emails a given domain is sending.

This can lead to negative customer sentiment, increased unsubscribes and even spam complaints which are harmful to your sending reputation. Focus your efforts where it counts the most, to your highly engaged subscribers who are engaging with your content and bring repeat business. Let those unengaged list segments go, it’s a strategy that will ensure long-term success and drive higher ROI from your campaigns.

Not sure where to start? Follow our reputation warming guidance or contact your Account Executive to learn more about our Deliverability Services offerings. These services provide expertise on key deliverability KPIs, bounce and blocklists, inbox folder placement, and sender reputation. The reporting format, frequency, and distribution can be customized to fit any customer’s size and budget.