Email Best Practices

How To Avoid Getting Into An Email Blacklist

Do you know the reasons why people might mark your messages as spam and you get hard bounces every day? Well, you know, there are smart spam detection mechanisms reacting to any suspicious action. What can be considered a suspicious action?

For example, you break some limits, add too many links and pictures, don’t use an email verifier to check the prospects lists, and so on. Even the smallest word may cause undesirable consequences, namely, you can be blocked. So, in this article, you will learn how to avoid getting into an email blacklist.

What is an email blacklist

A blacklist is a real-time list of IPs, domains, and email addresses that are marked as distrusted and result in a high number of hard bounces. If you break sending limits, send messages to invalid emails or to people who haven’t subscribed to your messages and who might consider your emails spammy, then you have a high chance of getting blacklisted.

How does it happen? You send an email to a person. The person’s mail server checks your domain authentication and reputation (behavior, bounces) and the content of the email as a copy, links, images, etc. At the end, it decides whether to land your email to the recipient’s Inbox or the Spam folder.   

To get into a blacklist is easier than to get out of it. So this is the dangerous thing you’d better keep out of.

How to avoid blacklists

Sometimes, it’s enough to break some rules and limits to get into a blacklist. Which ones? Well, let’s see.

Stick to email providers sending limits

Knowing the sending limits of your provider is really important. Why? Because otherwise your email campaign will get temporarily banned or your account may be blocked. Different providers have different limits. Choose the provider depending on the size of your campaign and send as many emails as you need.

So, using a particular email provider pay attention to:

  • Attachment size limit. If you want to use Gmail, for example, the max size of an attachment is 25 MB. And ICloud mail has 20MB, up to 5GB with Mail Drop turned on.
  • Messages per hour limit. Gmail has 20 messages per hour. And ICloud Mail has 500 recipients per message. So you need to know the limits of the hourly messages to set the delays.
  • Daily email limit. The total number of messages you can send each day with Gmail is 500 messages. And with ICloud Mail is 1000 messages. It makes a big difference.

Don’t buy email lists

Everyone wants to have big prospects lists, but how far can you go to achieve what you need? Well, buying email lists isn’t the best idea. Firstly, people on these lists haven’t directly given their consent to receive emails from you as a sender.

Thus they are likely to mark emails as spam because they probably don’t wait for a message from a zoo shop while they’re interested in cooking. Secondly, there’s a good chance that a catchall email (a spam trap, a fake email address made by an ESP to catch spammers) is included in the list. Sending emails to a spam trap will usually land you on a blacklist.

If we haven’t convinced you yet, here are some more reasons why you should avoid buying email lists:

  • High unknown user rate. Lists are sold by quantity. Unluckily, people that sell them are not always honest about the quality. You can’t be sure of their quality. ISPs see a high spike in unknown users as a negative flag on your reputation and will block or send messages to the Spam folder.
  • Extra money on verification. As you cannot be 100% sure that the email addresses on the list are the best ones, you need to verify them to be sure you won’t send messages to invalid emails. And that is no free of charge.
  • Spike in spam complaints. If people suddenly start getting messages with irrelevant information, they will report these emails as spam. You will see the spam rate going high as well as the complaints rate.
  • Drop in ROI. Disreputable lists have an absolutely low response rate, reducing ROI. Moreover, the effect of bounces, unopened deletes, and spam flags are factored into the sending reputation. These negative statistics suggest ISPs to block messages or filter them as spam.

Send unique emails

When you send emails, the ESP analyzes them. Which is why each message should look truly unique as if it was created specifically for a certain person. Here segmentation and personalization can help.

  • Segmentation. Create a prospects list and break it up into segments. Make up the smaller groups based on the data you have found about the prospect: demographics, geographical location, name, job position, hobbies, pain points, needs, etc.

    The more segments you have the better it is: the more unique emails will look as each one contains different information.
  • Personalization. Send the emails which are 100% personalized. Mention the customer’s name, the company name, the event name or any other info in the email.

    That means you don’t send bulk emails, where a copy is just a copy of a copy and is the same for everybody, but different messages for every prospect. And the system won’t block you. This way your approach will be more individual, as you contact every recipient face-to-face.

Source: Monetate

As you can see, segmentation and personalization are the key points to make every campaign and email look original and personal. On the one hand, the emails will look less suspicious to the ESP, on the other hand, people are more favorable to personalized emails.

Be patient with attachments

Once again, every email you send should include unique and bright content to attract the readers’ attention. But still, there’re limits you’ve got to stick to. If you use too many attachments, you will surely be blocked.

You should be careful namely with:

  • Pictures: they make everything brighter. But not all the email providers and devices open pictures in emails by default. Using only pictures in the emails is quite dangerous, add some text. The perfect ratio of text to pictures in an email is 70 to 30%.
  • Videos: just the same situation as with pics. The email becomes too heavy. The system takes some time to moderate it. And in the end, it may not be displayed correctly.
  • Links: including too many links will not serve you right. Not only because of spam filters but also because of people’s general distrust. Custom one professional-looking CTA link and attach it.
  • Fonts: use the appropriate font according to your content and audience. Don’t use Comic Sans MS to write a business offer. Business fonts are for business, funny fonts are for fun.
  • Colors: avoid a cacophony of colors, three colors are enough to be readable. Use the company’s corporate colors. Be mindful of what colors you are using: bright colors to evoke a response, neutral and dark colors to relax. Put an outstanding CTA button to make people pay attention to it and make a needed action.

All in all, just strive for a healthy balance of the above-mentioned things to avoid triggering spam filters and look suspicious to the recipients.

Don’t use spam words

Spam filters have become much more sophisticated. They use algorithms that track everything about you as a sender, including SMTP server information, domain information, links and pictures in your emails, your recipients and more. The filters can be triggered for a variety of reasons, and one of them is spam words.  

Choose words carefully, check out the spam words lists, and avoid using such words as “free”, “best price”, “buy now”, be creative, interesting, and informative.

Avoiding email spam trigger words won’t skyrocket your email deliverability to 100%. But also it won’t let your email messages end up in the Spam folder.

Verify emails

Email providers bounce any email sent to addresses that don’t exist. So, here you need an email verifier. This tool checks whether an email address is real, valid, and deliverable. There’s a usual practice when an email address is invalid.

The aim of the verification process is to clean up email lists and ensure that emails you send will reach the recipients’ Inboxes. And all these recipients are real people with valid emails.

With this tool, the bounce rate doesn’t go high and your reputation of a sender is under protection.

Choose an email verifier

So we’ve approached to the subtle question of email verification. Use email verification tools like the one provided by to validate each email address. Email Verifier meets all the requirements of a good verification tool, namely:  

  • Online service . Having an online service is far more convenient. The users can access it anytime, from any device.
  • Scalability . The service can verify both single email addresses and large email lists.
  • Catchall detection. The tool detects spam traps and marks them with “unknown status code”. So it’s completely your decision whether to send emails there or not.

You can verify as many emails on the list as your credit balance allows. And the great point is that the free account gives you 50 credits per month that reset every 30 days. But the main advantages of the Email Verifier are:

  • Speed and size. You can verify large prospects lists in a matter of minutes.
  • Convenience. The verifier tool is available not only as a web app but also as a Chrome extension. Once installed, you can visit any website page to find and verify leads.
  • All-in-one. The platform provides users with an inbuild finder tool, both web app and an extension. Using it as a web app, you can find emails and verify them in the blink of an eye. If you upload a list of email addresses to the platform, will email you when all of them are verified.  

Be careful

No one would like to be blacklisted for nothing. Or is it for something? Anyway, to be on top instead of being in the blacklist, you should:

  • Check the email provider’s limits. Attachment size, hourly and daily email limits.
  • Send personalized emails. Everybody likes getting messages that were composed only for them.
  • Verify email addresses. Download an email checker and you will have one problem less.

And you shouldn’t:

  • Buy suspicious email lists. Somebody gets them from somewhere. You can’t be 100% be sure this list is OK for you.
  • Overdo with different kinds of attachments. Videos, pictures, links, and colors in the email body are great but they trigger spam filters.
  • Use spam words. Replace them with harmless synonyms.

Success to you!