How to Avoid Spam Filters with your Email Marketing


You may think that avoiding spam filters is the holy grail of email marketing, but it’s not that complicated.

All you have to do is implement all of the best email marketing practices. Having said that, it’s not as easy as using an email marketing platform.

Most of the posts we have at sendXmail have a background on what clients and partners ask us through social media or when we have deep conversations with them. That’s how we know if it’s a valuable post for you.

A recurrent question, with subtle variations, was about why emails were falling into the spam folder if they were using an email marketing platform? As you may already read in this post on why email marketing is not a platform, there’s more to it than just a technology. Like any other brand communication channel, we must master what works well and what we need to avoid.

Why should we avoid spam filters?

It doesn’t matter how well you write your email and spend enough time with your subject line if people don’t have a chance to see it. Why don’t they see it? Because a spam filter marked your email as a potential spammer, which brings it into what it’s called a quarantine folder or spam folder.

If you want to be seen by your audience, you need to avoid spam filters.

What is spam, and why there are spam filters? Spam is a term designating unsolicited emails getting to our email account by companies, people or organisations.

Spam will be around 50% of all email traffic in 2020, according to SecureList by Kaspersky, with small oscillations along the quarters. To place things in perspective, spam represents half of all emails sent or received worldwide. Some people would argue that’s even more.

If you don’t want someone to tag you as a spammer, here are the best practices you need to implement on your email marketing or email server.

Use email sender authentication to avoid spam filters

It’s not enough to use a credible email marketing platform. It’s imperative to authenticate any email system that you’re the original and actual sender of those emails.

Why were the email sender authentication standards created?

As you can imagine, spammers, phishing, and spoofing emails or hackers can use your email address and send it to someone impersonating you. Even though the sender authentication standard is not a bulletproof concept, it can prevent most attacks made in your name.

At least, it can prevent your brand from being automatically blocked by spam filters and other security software that easily. Unfortunately, they can still do it, but you’re reducing your risk, almost like insurance.

What are the primary email sender authentication standards that you need to implement? There are plenty, but you’re already better than 90% of the other senders if you rely on these main ones.

Fortunately, we’ve already done an exhaustive study and step-by-step guide to implement on your email sender and avoid the spam filters. Here they are:

SPF and DKIM email sender authentication to prevent spam filters

These are the most standard, and most email marketing platforms or other email servers already demand their implementation. SPF stands for Sender Policy Framework, and it’s one of the most used since most hosting companies already place it with the DNS registry.

The DKIM stands for DomainKeys Identified Mail, and it’s the other of the most used email-sender standards.

You can see all the step-by-step guides to implementing SPF and DKIM email sender authentication here.

DMARC is one of the most recent email-sender authentications

DMARC is the acronym of Domain-based Message Authentication, Reporting and Conformance. It’s a very long name to say that it’s like an encrypted password or a series of DNS registries that identify if the email sent has the same correspondent key in the brand’s DNS registry.

You can see the step-by-step guide to implementing the DMARC email sender authentication here.

BIMI email standard is the most recent one

Everyone who deals with email marketing is already raving about the BIMI email standard for two main reasons:

  1. It’s a way to prevent our domain name from being associated with email senders that don’t have the authentication to send all emails directly to quarantine or be rejected immediately.
  2. It has an incredible marketing feature that makes all marketers drool over it. It shows the brand logo in those little globes next to each email in the subscribers’ inbox.

Take that as a reasonable email sender authentication procedure. Only the brands with all the authentications can present their logo when a Gmail user scrolls through their inbox feed.

You can check the step-by-step guide to implementing the BIMI email standard authentication here.

Separate your business emails from your marketing emails

At sendXmail, we’ve done our share of tests, and one thing seems to be consistent to avoid the spam filters. When you separate your business emails from your email marketing ones, you avoid any possible hassles.

Think about it as different cocoons to protect each end goal from the other. This way, if you do something wrong with your business emails, it won’t affect the marketing ones and the other way around.

The way you can do it is by selecting a professional email service provider for business emails like Gmail for Business, Amazon WorkMail, Microsoft Outlook Service, to name a few. That will provide a distinct cluster of emails with IP and DNS of their own, separate from the ones you’ll use for marketing or transactional emails.

How often did clients ask us to help them solve a complete domain and IP block caused by an “enthusiastic” sales executive that sent 5000 emails through their Outlook to a list of contacts without letting anyone know? 😓

The same could happen when the marketing team is testing something with their email marketing platform that goes sideways and can’t avoid spam filters. If it’s all connected, imagine all of your business and work emails are now being filtered and can’t reach their destination. It’s a complete nightmare. 😱

Use a professional Email Marketing Platform.

If you’re serious about your email marketing, you should invest in a professional email marketing platform. You have two choices with this decision. You can choose to go for a self-hosted platform or use a SaaS one.

At sendXmail, we’re entirely email marketing platform agnostic. Having said that, in most cases, the SaaS solution can be the best option due to the resources needed to have your email marketing continuously operating in top-notch.

Will this avoid spam filters on its own? Nope. But it’s one of the critical steps to do the best practice of this marketing strategy.

For example, you can fine-tune an email marketing platform to know how many emails per hour to send to each ESP (Email Service Provider). It’s the same as dividing emails per server to avoid being blocked—having the necessary unsubscribe, preference centre links and physical brand address. And one of the most important measures is sending emails with the correct sender authentication information.

To answer the previous question better, you can’t avoid the spam filters on their own, but it can help hugely to that purpose.

How many times did clients ask us to help them solve a complete domain and IP block caused by an “enthusiastic” sales executive that sent 5000 emails through their Outlook to a list of contacts without letting anyone know? 😓

Opt-in and Double Opt-in to avoid spam filters

Maybe this should be in the first place, but we decided to place it here to help you understand that it may not save you from the spam filters even if you have an opt-in or double opt-in process.

It seems redundant or incoherent, but you must understand that these spam filters base their actions on simple rules that trigger responses. If you collect X number of triggers, it filters your email into a spam folder.

You may have the subscriber permission, but the subscriber’s ESP doesn’t know that. They just react to what you’re sending them now.

However, if you don’t have an opt-in process and you’re sending without their permission, it’s like buying an express ticket to the spam folder for sure. That’s because if enough people click on the spam button, the ESPs will filter your email sender, domain name and IP immediately from now on. Believe us when we say that getting out of a spam filter is really hard.

It means that you should run away from purchased or rented email lists. It won’t do you any good, quite the opposite.

The benefit of a double opt-in process is that when people conclude their opt-in confirmation, they’re providing subtle signals to their ESP that you’re a reputable source of emails.

Especially when you suggest that your subscribers drag your confirmation email to their primary inbox. 😉

IP and sender warm-up to avoid spam filters

One of the most effective ways to avoid being filtered is by “warming up” your IPs. What is this warming up?

Imagine that you’re a patrol ranger, and you see a group of people you have never seen before coming up. The first time this happens, you’re going to ask them for a complete check-up, ID, what they’re doing and why.

The second time you see them, you’ll ask for more minor things. The third time, even less to worry about.

That’s what happens with IP warm-up. It’s sending small packs of emails daily for a week, then a bit more the next week, increasing every week. If you send immediately 100.000 emails out of the blue to a specific email provider, you won’t be able to avoid spam filters.

Check for spam traps or non-engaged subscribers.

One of the best ways to avoid spam filters is not triggering them. It’s paramount.

What activates a spam filter as much as a high spam rate? When sending emails that exist only to identify senders that scrapped their emails from the web or don’t make a database clean-up hygiene.

Ensure that you don’t have any spam trap in your list by adopting a full-proof opt-in process and conducting regular database clean-up routines. For example, remove subscribers who don’t engage with your latest newsletters for a long time—the same as those that keep bouncing for email full or some other error message.

A clean list is a gold standard.

Avoid spam filters checklist
Tips to Avoid Spam Filters

Personalise your content to avoid spam filters

Personalising your content can do wonders for your email marketing. Not only because it delivers relevant content to your audience but also inserts metadata in your emails with more than your subscribers’ emails.

It’s a clear sign that you know this person, not just an email scrapped from somewhere.

Use an actual email sender.

If you’re still using a “no-reply” email sender, you’re doing it wrong. Not only because you’re forgetting email is a bi-directional channel but also because you’re sending a bad signal to the spam filters.

Some ESPs may send captcha tests or reply emails with links to verify that you’re an actual sender and not an automated system or a bot.

Do prefer clean HTML code to avoid spam filters.

If you use code or copying-paste code with pre-formatted content from Microsoft Word, for instance, it can trigger these spam filters.

The focus should be developing clean HTML code without javascript or another programming other than simple text or HTML.

Having a code that can adapt to mobile or desktop is essential for the user experience as well. As much as your subscribers like what they’re reading, each ESP will receive better signals.

Avoid short URLs links on email content.

Short URLs can trigger more strict spam filters because many spammers or phishing scammers use this kind of service to hide the actual landing page.

Instead of short URLs, you should use the email marketing platform’s own tracking system. Remember that people can click on emails; you don’t need a short URL to remember the web address.

Don’t send emails entirely built by images

An email is not an Instagram feed. 😉

If you send an email with a massive percentage of images against text content, you’re dropping a considerable trigger that you might not be a trustworthy source. It can trigger the spam filters, but it’s also an email marketing bad practice since most people don’t have automatic image download activated.

If they can’t see what you’re saying in your email, the chances are that they’re going to delete your email or classify it as spam.

The waiting game is not your friend.

If you’re wondering, leaving too much time between your last email and the next will make it suspicious and raise red flags. You can relate this to one of the last tips mentioning the IP warm-up.

This happens because your sender history doesn’t match. Whenever you send sporadic emails, and then you start sending a more considerable volume of emails is not natural.

We notice something, especially with e-commerce when Black Friday and Cyber Monday happen once a year. They keep a low volume all year round, and when this time occurs, they send thousands of emails per day repeatedly because they know how much money they can make. The problem is that the spam filters are all in full force blocking your emails.

Keywords aren’t just for SEO

More than ever, we use keywords for various purposes. AI, Machine learning, algorithms for multiple goals and… spam filters use them. If your email content has lots of keywords usually associated with spammy emails, you have a great chance to be filtered.

For instance, if you are overdue with words like “Buy, call now, $, be your own boss, etc.” you can see a complete list here; the chances are that you’re going to end up filtered.

Quick note: You can still use all the words you can think of. In the past, we’ve used a copy that contained Viagra or Cialis, brands that were often used by spam emails just to prove a point. That we still could end up in our subscribers’ inbox. And we did.

We did reach our subscribers’ inbox because of our sender reputation and the general sum of all the little things. If we don’t overpass the critical number of triggers, we can pass even with a sketchy email, which we don’t advise you to do. Ever.

Wrap-up of how to avoid spam filters

Why don’t we sum up the major strategies to avoid spam filters to block your emails?

  1. Activate all the Email Sender Authentication standards you can.
  2. Ensure that you separate your business emails from your marketing and transactional ones.
  3. Use an email marketing platform that can handle most email marketing best practices.
  4. Your email list has to be opt-in or double opt-in. Grow it organically and avoid purchasing or renting email lists.
  5. Do a proper IP and sender warm-up before sending thousands of emails out of the blue.
  6. Avoid spam traps and conduct periodic email list clean-up.
  7. Personalise your content.
  8. Use the sender of an actual email and forget the “no-reply”.
  9. Use clean, standard HTML code.
  10. Avoid using short-links providers.
  11. Balance your images vs text email content.
  12. Avoid the long alternating absence of emails sent with the rapid surge of campaigns.
  13. Be aware of spammy keywords and avoid using a certain number of them.

Did you take notes? If you want to avoid spam filters, all you have to do is show that you’re sending what your subscribers asked you to.

It seems simple, yet it can be daunting. That’s why sendXmail has helped hundreds of companies to escape the spam filters and reach their audience.

If you need assistance, we can help. Just get in touch and tell us what you need.

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