Blacklist check: avoid a bad email sending reputation

Blacklist check can avoid bad email reputation

Let's face it, one of the biggest problems concerning email marketing (any kind of email marketing) is deliverability. It doesn't really matter if your follow every single rule out there, build the most incredible email with a great subject line, layout, images, links and so on. If the email doesn't reach the inbox you have just wasted time and money.

But what is email deliverability? How can it be influenced by a bad email reputation? How do you know if you have a bad reputation? What's a sender score? Why should you do an email blacklist check? We're going to try to answer these and other questions on this blog post. So stay tuned and follow our tips:

Email acquisition: the first mistakes

Most of the problems with deliverability start way back, at the beginning of the process, in the email acquisition. First of all you need your customer's permission. Using a double opt-in is a good strategy to make sure your list is trustworthy.

Second, tell your customer what to expect from your emails. This will prevent misunderstandings and future opt-outs.

When you have new subscribers the first logical step is to send welcome emails, right? Yes, you should do that. But to be sure you don't trigger the spam filters you should keep a low volume of welcome emails per day. Warm up your IP first. This will minimize the risk of being blocked because of a bad reputation.

A strong method to cover all these issues is to send a welcome series. This way you can clearly communicate your plan of action for your customers: from what to expect, when to expect, how to opt-out or change personal information.

As tempting as may be, stay away from purchased lists. Seriously. Chances are you will acquire a list of emails with out-of-date information, incomplete data and you'll get a highly chance of damaging your online reputation, which will send you straight to blacklists.

Email reputation: why does it matter?

I am sure you have faced this situation before: when analyzing your email metrics you suddenly realize that some of your campaigns did not reach the intended inbox. Well, my friend, you are not alone. Worldwide, one out of five commercial emails doesn't get delivered or, in other words approximately 79% of emails get delivered. But where do they go? They either go to a spam folder or are blocked by the mailbox provider.

There a few actions you could take to improve your email deliverability. But first, let's find out what is email reputation.

In a few words, email reputation or sender reputation is how the Internet Service Providers (ISPs) classifies your sending domain (e.g., or IP as trustworthy or not. You will then have a sender score that can vary from 0 to 100 (100 being the best one). The score is made up from the analysis of a few items:

  • Email volume
  • Complaint rates
  • Spam trap hits
  • Unknown user rates
  • Blacklist listings
  • Bounce rates

There are other items that can influence on your sender score as well:

  • Metrics: open rates, click-through rates, replies, forwards. Also known as engagement metrics.
  • Opt-outs
  • Abuse rates:how many clients have reported your emails as abuse or not wanted
  • URLs shorteners: a very common strategy used by spammers
  • Free domain email address

To find out your sender score you can go to websites like Return Path or Sender Score: free services that calculate the metrics for you.

Find out more about sender score

But why should you care about your email reputation? It's simple: email reputation is just like your personal credit reputation. If you have a bad one it´s not good for you and if you don't have one is not good for you either. If the ISP don't know you they might assume the worst and your emails might be blocked or classified as SPAM as well.

But how to prevent that? We will come to that. But first, another bump in the road: the email blacklists.

Email Blacklists: should you be scared?

If you have a low sender score you might end up on a blacklist. Blacklists or blackhole lists are usually created by the own email recipients that report your email as SPAM. The lists are a real-time public database that uses different criteria to list your IP or domain as spammers.

If you end up in one of this lists it means that your emails won't go through, or your will fail to hit the inbox.

There are various blacklists out there and they use different criteria to include IPs and domains in their lists. Basically, anyone can set up a blacklist for their own email server, but most ISPs only use reputable blacklists like SpamCop, Spamhaus and URIBL. The blacklists are basically a tool to help the ISP to make their decision to block or not to block some IPs.

To find out if you are in one of the main blacklists out there you can visit the top DSNBL lists such as Spamhaus, SURBL, Barracuda Reputation Block List and Spamcop. If you happen to be in one of these lists, follow the instructions to find out how to get out. High bounce rates could indicate you may be on a blacklist. The better way to keep out of these lists is to check and monitor your complaints rates regularly.

IP addresses appearing on just one of the 12 major blacklists had email deliverability 25 points below those not listed on any blacklists

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The quickest way to keep out of blacklists and prevent blocking is to focus on engagement, consistency and bounce rates. As we said before high bounce rates may indicate that you are on a blacklist so keep your eyes on the metrics. Consistency is the key to showing your customers that you are a serious organization. Send emails on a consistent and regular frequency. Your engaged customers are the ones that will help you throughout the process.Stick to the ones that usually open/click on your emails. Targeted, relevant content is still the best practice to ensure that. Keep your lists clean and always remove inactive subscribers.

Although it is considered a good practice to send emails to inactive users, know when to stop. By continuing to send an email to unengaged subscribers, you’re putting your reputation at risk (bounce rate), as well as increasing the chances of an inactive address being converted into a spam trap.

The little deliverability dictionary

When talking about deliverability there are a few terms that you must master to your improve your rates. We have selected 10 terms to help you:

  • Acceptance Rate: the amount of emails that have been accepted by the server. It doesn't mean that will reach the inbox, though.
  • CAN–SPAM Act: the rules that were created back in 2003 by American president George Bush to prevent email recipients to have their inbox flooded with SPAM. You must know every single one of them.
  • DKIM (DomainKeys Identified Mail): this is the digital signature that allows your email recipients to believe that the email was sent by a known sender. It's basically a method that associates the domain with the message, so someone can actually claim the responsibility for the email.
  • Double Opt-In: the safest strategy to make sure your list if filled with clients that actually want to be in it. The double opt-in is when you send an email to confirm that the subscriber has signed in.
  • Ham:the email that your client is waiting for and is not considered a SPAM
  • Hard Bounce: a hard bounce can have a big impact on your sender score. To make it simple, it is that email that keeps coming back due to an invalid, blocked or non-existent address.
  • Honeypot: a type of spam trap. Honeypot is an email address created specifically as bait to spammers.
  • Sender Policy Framework: the system that prevents a domain from sending unauthorized emails from other domain.
  • Spamtrap: email address used to lure SPAM.
  • Warming Up an IP: a strategy to build an IP good reputation. It consists of sending an ever increasing number of emails from the same IP address.

Transactional emails shouldn't generate complaints

Since transactional emails are system-generated emails triggered by an action of the customer, we are to assume that should be no complaints. After all, the customer is expecting your email. Well in theory, that is true. But sometimes this is not what happens. For instance, your transactional email may have spammy words, email attachments, broken images, missing tags, your HTML is not well coded, or your email contains only emails. If you make one of these little mistakes you might be filtered as SPAM, or even worst: your customer can hit the THIS IS A SPAM button and ruin your whole strategy.

So do pay attention to every little detail to ensure everything runs smoothly and you reach your target.

69% of email recipients report email as Spam based solely on the subject line

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Another piece of advice: although it's not common to add unsubscribe links on transactional emails it could be a good practice to do so. If you do that you can get engagement feedback and prevent sending emails to someone who has signaled they don't wish to receive it anymore.

Easy solutions

So besides everything that we have told you so far what else can you do to ensure that your deliverability rates are as high as you wish? Here is a checklist of actions:

  • Warm up your IP: as we mentioned before, start sending emails to address that are already engaged. With time increase the number of emails you send.
  • Register a subdomain: and use it only for email. This will make it easier to monitor your reputation.
  • Implement a sender policy framework: the email validation-system will increase your trustworthiness.
  • Check your sender score: and do the necessary changes to improve it if this is the case.
  • Check feedback loops: and find out how have complained about your emails.
  • Have a consistent schedule: random activity can cause lower sender score, so keep a regular schedule.
  • Use a double opt-in: the safest method to guarantee that your subscribers do want to receive your messages.
  • Check blacklists: and keep out of them.
  • Keep your contacts list clean: delete inactive subscribers. Check for wrong or invalid address.
  • Add from in your subject line: this strategy can also increase your open rate. Just add the from after the name of who is sending the email. Eg: Alex from Myshop.

Monitor your reputation closely. Follow your complaint and engagement rates, segment your users, personalize your content and test your campaigns. Incorporate these best practices and ensure that your emails are sent and delivered for customers that do want them. Prevent delivery failures before they happen.

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