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5 ways to ruin your sender reputation

Does your brand have a good reputation?


You’d better hope so.

According to a recent study by Return Path, delivery rates for emails from senders with poor sender reputation scores are markedly lower than those for senders whose reputations are strong.

How much lower?

A LOT lower…

6 ways to ruin your sender reputation

This difference in delivery rates can represent massive amounts lost revenue, especially for brands with large mailing lists.

And isn’t revenue what this is really all about?

What is a sender reputation or sender score?


Sender reputation is measured by a score that an Internet service provider assigns to the IP address sending an email.  ISPs then use these sender reputations as a way to determine whether a sender’s email is legitimate or not.

Think of a sender score as a credit score. You want a high sender score – the higher the score, the more likely it is that an ISP will deliver emails to recipients using their network. Just like how a low credit score can block a person’s chance of receiving more credit or loans, if the sender score falls below a certain level it’s likely that your emails will be blocked from a recipient’s inbox. When filtering emails coming from a sender with a low score, an ISP may automatically reject emails and deliver them to recipients’ spam folders instead of their inboxes.

As with all things related to Internet formulas and algorithms, a variety of factors go into determining an organisation’s sender score, including (but not limited to):

  • How many recipients flag the emails as spam
  • If the organisation is marked on blacklists
  • The sheer amount of email an organisation sends
  • How many emails bounce
  • How many recipients unsubscribe from the sender’s mailing list

How a bad sender score impacts email marketing performance


According to the Return Path study cited above, out of more than four trillion emails sent in 2015, a whopping 56% were blocked based on “poor sender reputation”. The study shows that senders suffered if their score was below 70 (with an average delivery rate of just 9%), while senders with a score above 71 “saw an average delivered rate of 93 percent and represented 90% of all email delivered in 2015”.

Clearly, sender reputation has an enormous impact on emails actually making it into a recipient’s inbox.

The study also asserts that senders with low scores “aren’t even considered by mailbox providers”, although it is worth noting that a high sender reputation score isn’t the only factor that determines whether or not your email makes it to its final destination.  

How to manage your sender reputation

Each Internet service or mailbox provider has its own formula for scoring incoming mail.

Additionally, according to Return Path, certain mailbox providers like Gmail, Microsoft, Yahoo, and AOL ‘take individual engagement levels into account when considering how to filter messages’

With so many elements involved in getting an email delivered, what should email marketers avoid to protect their precious sender reputation?

We are not talking about the obvious “black hat” issues affecting sender reputation, like buying mailing lists (don’t do it!) and sending spam emails (God, no!).

If your brand is engaging in such practices and plans to continue doing so, there isn’t much that can help you.

However, even brands that don’t dabble in dodgy practices could still be doing significant damage to their sender reputation without even realising it.

Here are a few of the worst offenders…

5 ways to ruin your sender reputation

1) Using spammy subject lines


If it looks like spam, sounds like spam and reads like spam, chances are it’s….spam! Not only will this make subscribers more likely to send your emails straight to the “spam” box,  but ESP and ISP filters will take note and your sender reputation will suffer. Make sure your subject lines are on point at all time.

2) Emailing subscribers too frequently

Image credit: CBS


All your marketing emails should be providing obvious value to your subscribers. If you start emailing too frequently (or with nothing to say) it may look to your subscribers like you’re trading in quality for quantity and wave a big ‘ol red flag to the ISPs.

3) Offering nothing of value


Whether you’re emailing too often, too seldom, or just the right amount, if there’s nothing of value in your marketing emails your subscribers will be turned off quickly. You’ll soon start to see your sender reputation plummet, and everyone will hate you, including those fine folks at your local ISP.

4) Not maintaining your email list

Image credit: Walt Disney


High bounce rates can negatively affect your sender reputation. With this in mind, it’s a smart idea to regularly scrub your email list of both invalid emails (which produce hard bounces) and non-responders (you don’t want it to look like your messages are regularly falling on deaf ears). Keep your list clean!

5) Employing dishonest or deceptive subject lines

Image credit: Nickelodeon


Similar to using spammy subject lines, going down the clickbait trail will lead to subscriber annoyance, unsubscribes, and low engagement. No one wants to open an email because it sounds interesting just to find the content of your email sucks. Keep your subject lines clear, honest, and effective.

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