Email Marketing, Sales Funnel Creation

How To Avoid Email Spam Filters – 4 Key Factors

 May 14, 2019

By  Peter Nyiri

If you’ve been sending emails, you already know that your emails may go to your recipients’ junk folders. Did you know that this may have nothing to do with spam?

Preventing your emails from going to junk folder is one of the most tricky parts when doing outreach or email marketing, regardless if you want to promote your online course or a product.

The first thing you’ll may notice is a rather weird behavior. When you send emails to Gmail accounts, they may get correctly delivered, while they’re marked as spam in Hotmail accounts.

This suggests the first important conclusion: mailbox providers adopt different techniques to decide when an email is or isn’t spam. Even when you send from a personal domain, there is no guarantee.

Why Is This Message In Spam?

Unfortunately your email client may not be telling you the truth.

The screenshot shows an eye-opening example.

similar to messages spam filter


Why is this message in Spam? It’s similar to messages that were detected by our spam filters.

Based on Gmail’s note you may get the idea that the problem is content-related, however that isn’t the case.

All their emails were landing in my spam folder, even though they are a trusted website – Paid Memberships Pro.

It is the latest update for their membership plugin that has 80,000 installations. Clearly valid traffic for users that are subscribed.

Here is another example that is even worse – I am trying to reset my password on my own site and goes into spam:

funnelxpert password reset marked spam

In fact if you have a new site, you can be almost certain that your WordPress notification emails will have this problem.

The 4 Main Factors of Spam

If your emails are going into the spam folder, the first task is to determine what category the problem falls into. There are 4 distinct categories for the cause.

  1. Server or IP address
  2. The technical setup of sending your emails
  3. Email content
  4. Sender reputation/ being marked as spam

1. Server/IP Address Problems

Listed In Spam Database

It’s not uncommon for web hosting servers to have been misused by spammers to send out unsolicited mail to users. For this reason, their domain or IP address are marked as spam.

If you are on a shared web hosting provider, you may experience this problem. It could be a good idea to get yourself a VPS or a dedicated server hosting because you will be allocated a unique IP. It is easy to verify if this is the problem.

As an example, I have recently purchased a cloud server and I also purchased an expired domain to run the server with.

Then I set up a website on the server, and everything was going to the spam folder.

I did a check in MX Toolbox:


“We notice you are on a blacklist.”

The screenshot shows that the reason why this domain is in the SpamHaus database is because the IP address was listed.

But why was the IP address listed?

Because the hosting server’s domain (SaadHost.com) was blacklisted and for that reason its IP address was also blacklisted in SpamHaus:



I had to go to the SpamHaus website and request the removal:

Spam DB removal

The IP was marked for “Manual removal only”.

The first thing I was asked to do was to provide a domain email address and click on the verification link.

spam DB verification email

Then next day I received an email:


This domain has been around since 2012 and has been listed for much of that time.
Did you, perchance, buy this on 23rd April?

I provided the answer that I purchased the domain in April and the domain was removed from the blacklist.

I had to do a similar removal request for the IP address.

Reverse DNS Lookup

> Warning – this is very technical. <

If you have professional hosting, this probably isn’t an issue and you can skip this. However if you have your own VPS, you need to watch out for this.

Let’s say the hostname of your server (such as SaadHost.com) has a domain DNS zone pointed to a given IP address.

The so called “Reverse DNS Zone” makes it possible to look up the primary hostname (SaadHost.com) assigned to an IP address. There is a so-called PTR record that is used for this reverse DNS (rDNS) lookup.

This procedure provides trust that the given hostname (SaadHost.com in this example) is the main domain connected to the given IP address.

The PTR record is a must have for outgoing mail servers, because most of the mail providers reject or mark as spam messages received by mail servers without valid reverse DNS configuration (missing PTR or if the PTR record and hostname IP address don’t match).

In my case the server domain BestSEOProduct.com resolved to the IP address 192.xx.yy.zz, while the IP address pointed back to SaadHost.com. This mismatch resulted in the emails sent from both domains getting marked as spam.

2. Technical Side of Fixing Email Sending Problems

The basic problem with sending emails is that some other entity, a mail server, sends it on your domain’s behalf.

And guess what spammers do… They send emails on someone else’s behalf.

Let’s say my domain is FunnelXpert.com – but my email will be send by SaadHost.com, SocketLabs,com, Mailerlite,com or whatever provider I use.

How does an email client like Gmail or Yahoo knows that the mail server is authorized to send on my email’s behalf and it’s not a spammer using my domain?

The answer lies in SPF, DKIM and DMARC.

spf dkim dmarc

Sender Policy Framework – SPF

Sender Policy Framework (SPF) is an open standard specifying a technical method to prevent from address forgery in email messages. SPF allows the owner of a domain to specify which mail servers they use to send mail from that domain. Before diving further into SPF, it is first critical to understand that email messages actually have two different “From” addresses.

  1. The first is the return path address. It is a value that is also called the “envelope from” or “mail from”. The return path address informs receiving mail servers where to return, or bounce, a message back to if there is an error. The return path address is not displayed to the recipient.
  2. The second address is the one that is visible to recipients and is located in the headers of the email message. It is also called the “header from” address or the “friendly from” address. Since this is visible to recipients it is the only from address that most people are aware of in an email.

SPF specifically protects and authenticates the return path address used in the message delivery process.


Every major mailbox provider and anti-spam system have implemented SPF authentication checks, including:

  • Gmail/GoogleApps
  • Microsoft/Office365
  • Yahoo
  • AOL
  • Comcast
  • RoadRunner
  • Verizon


If you do not already have an SPF record for your domain:
1) Log in to the administrative area for your domain.
2) Locate the page from which you can update the DNS records.
3) Create a TXT record containing a text like this, depending on your mail server (e. g. authenticating Google Apps):

v=spf1 include:_spf.google.com ~all

Adding another record would change the above example to:

v=spf1 include:_spf.google.com include:email-od.com ~all

This would allow both SocketLabs and Google Apps to transmit messages on-behalf of your domain.

Keep in mind that changes to DNS records may take up to 48 hours to propagate throughout the internet.


Adding a valid SPF record to your domain is a best practice, but is not enough to achieve a passing SPF alignment result for DMARC. By default, the “relaxed” alignment settings in DMARC require that the organizational domain used in both of the two “From” addresses are the same. That means if the domain you use in your from address in the message headers is [ @example.com ], then your return path address also needs to use an email address like [ @example.com ] or a subdomain such as [ @bounces.example.com ].

To check that you record is properly established and syntactically valid you can use any of the following third-party resources:

Kitterman SPF Verification Tool

Dmarcian SPF Survey Tool

DomainKeys Identified Mail (DKIM) Authentication

DomainKeys Identified Mail (DKIM) is a popular email authentication technology that allows for a domain to prove it is responsible for a message and that the message was not altered as it traveled the delivery path.

DKIM is a standard based on two previous authentication technologies, the DomainKeys standard from Yahoo and the Identified Internet Mail standard from Cisco. DKIM was formalized as a draft standard by the IETF in RFC 4781, published in May of 2007.

The basis of DKIM is that with the use of public keys published in the DNS records, messages can be authenticated in a non-path-related method. The authentication process revolves around the creation and decoding of what is called the DKIM signature. DKIM signatures are inserted into the header of an email message. A hash of the body and select header items is created and used in a calculation along with a private key value to create a message signature that can be decoded properly only with the public key which is posted in a domain’s DNS.

postman smtp in spam

WordPress Email Delivery

Many spam filters, especially GMail, treat WP emails with suspicion. This is with good reason. Servers can be set up to auto generate and send thousands of spam emails per hour.

In fact, I just sent a test email.

  • When the “From” address was wordpress@mysite.com, the message came to the spam folder (screenshot above)
  • When the “From” address was peter@mysite.com, the message came to the in-box

There are other reasons why the ‘From’ address can be the culprit.

If you are using a contact form or plugin that sends email, be sure the email is directed to a non-domain email, such as Gmail.

The purpose is twofold.

  • You will see if your emails get delivered correctly
  • Many people use the Gmail app to send, receive and answer domain email, in this case the sender and the receiver may be identical (it happened to me). Such emails will be considered impersonation and marked as a dangerous email automatically.

spoofing email

Using a CDN

If you use a CDN, your name servers get changed and this may result in unforeseen results in your email delivery.

Replace WordPress PHP-Mail With SMTP

You might have had trouble with WordPress emails going into your spam folder.

This is a common problem with emails that are sent from a website via PHP (the programming language that WordPress is based on).

post smtp

The easiest way to fix the spam problem is to use an SMTP plugin. These plugins use the SMTP protocol to send email rather than the WordPress PHP email function.

SMTP (Simple Mail Transfer Protocol) is a mechanism that authenticates all outgoing emails to ensure that they are signed by the server before sending. By authenticating via SMTP, you are sending your emails from a real user account, and your emails will be less likely to be marked as spam. WordPress can send emails by SMTP with an authentication plugin that connects your site wp_mail function with a valid email server.

You will need an SMTP provider, such as the one that comes with your web hosting account or an external provider like SendGrid or Gmail. You’ll also need to find your SMTP server details and username and password.

Post SMTP is an SMTP plugin. Just download it and activate. You’ll need to run the setup wizard and input your SMTP details.

Gmail SMTP: Gmail, the email service by Google, allows you to send out secure emails to your subscribers and customers directly from your site by authenticating via SMTP. (2,000/day max). The Gmail SMTP plugin connects your website’s wp_mail function with Gmail securely through the OAuth 2.0 protocol. In this way, you do not need to save your SMTP password on your WP dashboard.

If you run a successful e commerce or membership site that sends out a lot of emails, you will need a transactional email delivery service. These services are designed to handle sending large volumes of transactional emails (invoices, notifications, etc).

Such services are different from email newsletter services like MailChimp and AWeber. They only send transactional  emails and have different arrangements set up to ensure your emails avoid the spam folder.

Some have agreements with Gmail and Yahoo, etc., some use other methods, therefore results are not the same.

What Are Spam Traps

ISP’s first line of defense against spammers are spam traps. They are actually email addresses designed specifically for identifying and tracking spammers.

If your email hits such an address, you are immediately flagged as a spammer by the ISP. Your IP address and your ‘from domain’ get blocked, your deliverability rates plummet, and it can take you up to a year to restore a good sender reputation. This is how pure spam traps function. Pretty scary!

Another thing to worry about are recycled spam traps. They are inactive email addresses that ISP acquires after a certain period of inactivity. If your email hits such an address, the consequences are not as serious. Either your ESP or the ESP of your client will send you a notification of the bounce to let you know you are emailing a dormant address. But, if you continue to send emails to hard bounces, the ISP will eventually record it as a spam trap hit.

spam folder count

3. Tips To Avoid Spam Filters

Spam filters are a program that, by using different criteria, filters out unwanted and unsolicited bulk mail, thus preventing it from ever reaching email inboxes. .

Here are the things to take care of to avoid spam filters:

a. Personalize your account

Send emails from an email address that contains your personal name with your brand name so that the recipients recognize you.

Why? Simply because in the sea of emails they receive every day, they have to choose which ones to open. And people prefer to open those which include a personal name in the ‘from’ box.

43% of email recipients will click spam based solely on the info they see in the ‘from’ field, name and email address.

Leading Email Service Providers (ESPs) also pay close attention to the ‘from’ field. Spam technology also has reputation based filtering that gathers information about the source of the message (IP address and domain) among other things. Changing the email address frequently will confuse the receivers that will feel tempted to mark you as spam.

You can prevent this from happening by avoiding:

  • frequent changes of “from” field names
  • obscure ‘From’ field names such as: 1258gps@doman; noreply@domain; support@newdomain.com

Your email could yours, your CEO’s, your sales people’s. It could be whoever would be in charge of customer conversations.

For example, my two new emails have these two variations:

  • peter@mydomain.com
  • peter.n@mydomain.com

Personalizing your account is all about showing your credentials as a human being.

Add a profile picture and an email signature.

For best results, include the following details in your email signature:

  • Name
  • Job title
  • Company name
  • Address
  • Phone number
  • Email address
  • Website

email service providers

b. Choose the right Email Service Provider

People believe that all email service providers are the same. Not true.

Email Service Providers gain reputation based on the reputation of their clients.

Stay away from disreputable ESPs, as their IP addresses get blocked by Gmail, Yahoo! Mail or Hotmail.

You also need to select the right email service provider for the right purpose.

When sending cold emails, it is not recommended to use Gmail. It is better to go for a Microsoft account or an SMTP relay provider (e.g., Sendgrid).

c. Warm up your Email Account

When you have a new email address or a new provider, you have a neutral reputation, considered suspicious by the host.

If you begin sending tons of emails automatically from an address on a new domain, you confirm your host’s suspicions that you may be a spammer.

Warming up techniques can be done by sending emails to colleagues, friends, relatives from where you can get a reply. Act like a real person. Sign up for things using your new email address.

Create accounts on platforms. Join mailing lists. Sign up to at least ten things or even more. Then confirm your email address for each account and newsletter you’ve signed up to.

Act human.

The idea is to create a communication that increases your account’s deliverability rate and daily email sending limits.

Adjust your sending calendar to ensure your sent messages are spaced out, and run the campaign over a longer period of time to limit how many emails are going out each day

Then increase the volume of emails week by week and you can reach up to 1000-1500 emails per day.

mail tester score

d. Test before sending

It is always a good idea to test your emails before you actually send them to your subscribers.

You can use Mail Tester to check your spam score by sending a test email. It mimics spam filters and tests for spammyness. The score you get might help you improve deliverability.

If you have an inactive list or one that you haven’t emailed regularly, verify the email addresses with a verification service before sending/

e. Keep your email lists clean

To avoid spam traps and spam filters it is essential you keep a good email list hygiene. Here are some tips to help you with that:

f. High Bounce Rate

Email bounce has two types, soft and hard.

Soft Bounce = the recipient’s mailbox is full or there is any technical glitch on the recipient’s side

Hard Bounce = the email address is not found or domain name doesn’t exist.

Multiple Soft Bounces = Hard Bounces. Both types affect deliverability.

Purchased email lists contain info that is out of date, contain inactive or dormant addresses or even recycled spam traps.

g. Clean your mailing lists

If some of your subscribers are not opening and reading your emails, you should act.

Inactive subscribers damage the reputation of your domain. So, either launch a re-engagement campaign or unsubscribe those you don’t get a feedback from.

Sending a number of emails to an inactive address will eventually be recorded by the ISP as a spam trap hit.

Bounce rates have already been mentioned.

Bad reputation will damage your deliverability.

Pay attention to the notification of the bounce ISP sends you and delete the email from your list.

h. Use double opt-in

Make sure your subscribers want to hear from you.

Upon subscription, send them a confirmation email.

This is a simple way to stay out of trouble.

Spam bots fill opt-in forms they come across. Emails sent to those addresses are trouble.

Also ask subscribers to add you to their address book, it signals to the ISP that your subscriber wants to receive your emails.

i. Sending emails with multiple recipients in CC or BCC

Sending emails by putting many recipients in the CC and BCC field is a huge no-no.

spam trigger words

j. Stay away from spam trigger words

Spam trigger words – words that are considered spa in email

To avoid hitting spam filters and getting caught in them, pay attention to the wording of your subject lines.

Certain words and phrases, suchm as ‘free’, ‘best price’, ‘cash’, ‘no obligation’ have been blacklisted owing to their association with the spam mail. Recall all those emails we used to get that offered a free prize in the subject line in return for following a couple of steps of which you learn once you open the email.

Spam trigger words were usually collected from emails such as these, and should be avoided.

k. The email body

Spam filters rigorously scrutinize your copy as well. ISPs go as far as to mark emails as spam based on the specific content or images.

Everything matters, the design, the fonts, the attachments, the embeds, the images, everything. Even the most bizarre things, such as using the word ‘viagra’, can alert the spam filters. The devil is in the details, and here, the best policy is to keep the details to the minimum and to simplify, as much as possible.

spam email fonts colors

l. Avoid rich media content

A majority of email clients don’t allow the ability to view rich media content, such as video embeds and Flash, so avoid putting them in your emails.

If you do insert them, and they don’t show or work properly, it will look messy. This can damage your credibility as the email will seem spammy.

If the media content is essential to your marketing campaign, put it on your website and insert a link to it in your copy.

Also, avoid using JavaScript and other dynamic scripts, as they will alert the spam filters.

m. Avoid including attachments

Attaching files to your emails, like Word documents or PDFs, alerts spam filters immediately. Attached files also increase the size of your email, so consequentially, it takes them longer to load.

Instead place the document on your website and provide a link, or a CTA that leads to the document’s location.

spam fonts colors

n. Tone down the fonts and colors

People seem to pay a lot of attention to the fonts and colors used in the copy. Over 60% of the people surveyed found it unacceptable if the email marketers used irregular fonts, different font sizes and font colors. And over 70% of people declared that they prefer one size fonts.

Irregular font colors and sizes also alert spam filters, and the same goes for invisible text (white font on the white background for example). So simplify!

o. Cut back on the images

Even though we live in an era where pictures and images dominate all spheres of life, it seems that in email marketing you can have too many.

Including a lot of images, or big images will increase the load time of your email, which can affect deliverability rates.

Making your copy in the form of one big image will also probably get it stuck in spam. For example, Microsoft Outlook doesn’t recognize background images so an email like this will probably not be displayed correctly.

p. Optimize for Open and Response Rates

Engagement is the name of the game. Do everything you can to get recipients to open your email, and respond to its message (whatever that may mean).

This also means evolving your copy over time. Beyond just a strategy to keep your engagement high, we’ve seen lots of accounts who ended up seeing worse and worse deliverability rates even with high-quality lists and good copy, because they used the exact same copy for months and months.

One easy way to make sure your copy is staying fresh and ahead of spam traps is by consistently AB testing it.

A service like GlockApps will help you get out of the Promotions tab (you want and need to hit the inbox and only the inbox). It’s $39/month, but provides placement results – Inbox, Tabs, Spam, Missing – and why you’re landing there.

q. Get a certificate by a third party

There is also a possibility of getting a sender accreditation by a third party that acts as a guarantee to the ISPs that you are not a spammer.

There are companies, like ReturnPath, that assess your email practices and certify you as a trusted sender. This certificate guarantees that your emails will reach a majority of the inboxes you send emails to since it signals to ISP to let your emails bypass spam filters.

This is not a free service but is probably worth investing in since the money you spend can return with increased conversions.

mark junk

4. Avoid People Marking Your Emails Spam

a. Make it easy to unsubscribe

Always include an unsubscribe button or link in all of your emails. Thus you protect your reputation and credibility with your clients and the ISP. An unsubscribe is much better than being marked spam.

b. Follow-up

Regular communication with your readers/clients will help you keep your list engaged. Many unsubscribe after a longer period of inactivity. You will also see the inactive ones, preventing them from cluttering your email list.

c. Correct spelling and grammar

Proofreading should be a component of every email campaign. Typos and bad grammar will damage your credibility and make you seem unprofessional. 80% of the people surveyed find grammar and spelling errors a huge offense.

d. Don’t make false promises

Always align the subject line with what you say in the email. If your email copy doesn’t correspond with the subject line, it is more likely people will mark your email as spam. 69% of the people will mark an email as spam based on the subject line they see.


Per email etiquette, using upper case to write words and sentences is seen as shouting, and is considered rude. So avoid using all capital letters in the subject lines.

Subject lines written in uppercase will not only annoy the receivers, who will feel tempted to mark your email as spam, but it will also alert spam filters.

Don’t create drama and sensation by using multiple exclamation points because they will come across as spammy to the receivers and to the ISPs.

In order to draw people’s attention, create a witty, inquisitive subject line with a question mark – these have 44% higher open rates than those that contain exclamation points.

f. Respect unsubscribers

It’s the law. If people want to unsubscribe, let them go. They won’t buy from you anyways, they just poison your list.

If you continue to send them emails, they are likely to mark them as spam, which will hurt your sender reputation and reduce email deliverability.


Unfortunately, there is no magic formula that guarantees your emails won’t land in spam.

By paying attention to technical issues, cleaning email lists, taking good care to avoid all spam triggers in the subject lines and email bodies, and by following up appropriately and in a timely manner, you are more likely to preserve your credibility, sender reputation and protect your IP address and domain from ever getting blacklisted.

Peter Nyiri

Peter Nyiri

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