How to strengthen your sender reputation

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Learn best practices to strengthen your sender reputation for better deliverability.

If you're experiencing deliverability problems, your next step is to determine whether these problems stem from sender reputation issues within your control. You can also read more about using a dedicated sending domain.

If you're a brand new sender, it is important to establish a good reputation upfront. This, in turn, will allow you to gradually send to a broader audience while maintaining a good reputation and high open rates. On the other hand, if you've damaged your sending reputation, these best practices will help you get back on track and rebuild engagement.

Send to an engaged segment 

Most major email clients (like Gmail and Yahoo) track how recipients interact with emails from your domain. Specifically, they look at:

  • How many emails are marked as spam
  • How many emails are opened
  • How many emails bounce

They use this information to determine where your emails will be placed — whether they land in your recipient's primary inbox or spam folder. This means that, if several people mark one email campaign as spam, the odds of your next campaign landing in the spam folder for all of your recipients are higher. Gmail, in particular, looks closely at how recipients engage with your emails. If you send regularly to lists or segments where a percentage of recipients haven't opened an email in 3-6 months, Gmail will start to place your emails in spam for all recipients.

Creating segments in Klaviyo makes it easy to isolate engaged and non-engaged profiles so that you know which audience to target with email content.

  1. Isolate all inactive profiles in your main list in an unengaged segment. A good definition to use here is: has received emails for 6+ months but hasn't opened an email in at least 4 months.
  2. Next, create a very engaged segment of your main list. This segment should include subscribers who have clicked or opened at least one email in the last month.
  3. Send exclusively to your very engaged segment for  2-4 weeks.

This will help you build up your sender reputation with Gmail and other email clients. Once you've sent to a very engaged segment for 2-4 weeks, check to see if your open rates have increased.

With the release of iOS15, macOS Monterey, iPadOS 15, and WatchOS 8, Apple Mail Privacy Protection (MPP) changed the way that we receive open rate data on your emails by prefetching our tracking pixel. With this change, it’s important to understand that open rates will be inflated.

If your campaign analytics show a large number of iOS openers, we suggest identifying these affected opens in your individual subscriber segments.

For complete information on MPP opens, visit our iOS 15: How to Prepare for Apple’s Changes guide.

If open rates have risen, you can choose to adjust this engaged segment's definition or create a new engaged segment to include more profiles. For example, include subscribers who have clicked or opened at least one email in the last 2 months.

After another few weeks, you can expand this definition to those who have engaged at least once in the last 3 months. That's where we recommend you stop since sending to those who haven't engaged for 4+ months is known to catch the eye of email clients that use engagement to determine inbox placement.

After creating your inactive segment, it may be tempting to try and regain unengaged users with a winback campaign right away. However, we recommend waiting until you've sent to your highly engaged list for at least 3 weeks. If you try to send a campaign to these inactive profiles before making an effort to improve your sender reputation, it's likely that this campaign will end up in spam for most recipients. Instead, consider creating a winback flow to reach out to unengaged profiles.

If you attempt to re-engage inactive subscribers and are unsuccessful, we recommend suppressing them or otherwise ensuring they remain isolated from your main sending list moving forward.

Strengthen sender reputation for a specific domain

If you notice that your open rates only suffer for a specific email domain, you can take steps to improve your sender reputation for this domain. In this example, we'll use Gmail. 

To expedite the process of improving your sender reputation with Gmail, you will need to do the following for your next 3-5 campaigns:

  • Remove all Gmail addresses from your regular sending lists.
  • Create a segment of Gmail addresses that have recently engaged with your campaigns and separately send to this segment alongside your regular sending list.

How to exclude all gmail email addresses from a sending list

If you have a standard list that you are planning to target with a campaign, you will want to create a segment of this list that excludes Gmail addresses.

To do this, create a segment with two conditions:

  • If someone is in or not in a list > Person is in [insert list name],
  • Properties about someone > Email doesn’t contain 

Segment of subscribers excluding those on Gmail

If you have a pre-existing segment that you plan to target with a campaign, add a new condition to this existing segment— using an AND connector— to exclude all Gmail addresses. To do this, add the following condition:

  • Properties about someone > Email doesn’t contain

How to build an engaged segment of Gmail subscribers

Now that you excluded all Gmail addresses from your regular sends, you will want to separately send to engaged Gmail addresses. First, isolate all Gmail addresses on your regular send list that are highly engaged.

Use an aggressive definition of engagement here. Depending on how often you send, this can be has Opened Email at least once in the last 2 weeks or has Opened Email at least once in the last 7 days.

For example, if you use the latter, your segment will include the following conditions:

  • If someone is in or not in a list > Person is in [insert list name]
  • Properties about someone > Email contains
  • What someone has done (or not done) > has Opened Email at least once in the last 7 days

Segment of highly engaged Gmail users

If you typically send to a specific segment, you will want to add two new conditions to this segment— using AND— in order to only include engaged Gmail addresses. Add the following conditions:

  • Properties about someone > Email contains
  • What someone has done (or not done) > has Opened Email at least once in the last 7 days

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