Comprehensive Spam Filters Guide: How to Keep Your Mail From Going to Spam

Comprehensive Spam Filters Guide: How to Keep Your Mail From Going to Spam

While the spam folder can help filter junk email from legitimate emails in your inbox, sometimes emails wind up in the junk folder that you don't want to go to spam. There are several reasons for this and ways you can prevent emails from going to spam. In this post, we'll review exactly what spam email is, the different triggers for spam filters, and how you can make sure only spam emails go to the spam box.

What is Spam Email?

Spam email is a type of unwanted and unsolicited email that businesses or other entities may send out to long lists of recipients. 

In most cases, spam emails aim to sell products or services to recipients, but they can also contain viruses, phishing links, and other malicious materials.

This is why it's important to have spam emails sent to a separate folder from your regular inbox.

What is the Spam Box?

The spam box, also known as the spam folder or junk folder, is a designated location for storing spam emails once the email system filters them. The user's email program may create a spam box, or the mail servers may generate them. 

The purpose of this box is to keep all junk mail out of your main inbox to prevent clutter and increase safety. Every email program has a spam filter that helps sort legitimate mail from junk mail, sending the latter to the spam folder as needed.

How Does Email Filtering Work?

Different mail service providers will use different methods to separate spam emails from regular emails. However, they all function fairly similarly to help keep the inbox and spam folder consistently separate. 

For example, some email service providers may attempt to filter the following emails from inboxes:

  • Emails with no content — Oftentimes, emails that don't contain any content in the body function as tests for spammers to confirm whether an email address is valid, only for the spammer to send more spam emails later.
  • Phishing emails — Many spam emails contain links to phishing sites in an attempt to get users' personal information, including login credentials, names, phone numbers, credit card information, and social security numbers. However, scammers can use certain tricks to keep phishing emails out of spam folders, making it important for users to keep an eye out for these. Keep in mind that no bank or other legitimate businesses will ever ask for sensitive information via email. Only enter this information directly on the company's website.
  • Spoofed email addresses — These are email addresses that closely resemble a legitimate business or personal email address. They may feature a slight difference, such as a changed letter or number, which email systems may catch.
  • Unconfirmed sender — In some cases, the email system may be unable to determine whether an email came from a valid sender.
  • Emails previously marked as spam — Users may have already marked certain emails as spam, enabling the system to look for similar emails and automatically send them to the spam folder.
Email filter

What Triggers Spam Filters?

Spam filters are designed to identify and filter out unsolicited, unwanted, or potentially harmful email messages. Several factors trigger spam filters, which can be broadly categorized as content-based factors and reputation-based factors.

Here are some common triggers:

  1. Common Spam Keywords and Phrases
  2. Email Subject Line
  3. Sender Reputation
  4. Formatting and Content
  5. High Email Bounce Rate
  6. Email Volume and Sending Patterns
  7. Too Many Images in Emails
  8. No Unsubscribe Links in Emails
  9. Poor Spelling and Grammar
  10. Including Too Many Links
  11. Requesting a Suspicious Action
  12. Spammy Subject Lines
  13. The Inclusion of Irrelevant or Suspicious Attachments

Common Spam Keywords and Phrases

Spam filters are triggered when they identify certain keywords and phrases commonly associated with spam. These may include words related to money, offers, or adult content. By identifying and flagging messages containing such terms, spam filters help to protect users from potentially harmful or unwanted content.

Sender Reputation

Spam filters also take into account the reputation of the sender. If an email address or domain has been previously associated with sending spam or malicious content, emails from that address may be flagged or blocked. Maintaining a positive sender reputation through responsible email practices can help ensure that messages reach their intended recipients.

Formatting and Content

The formatting and content of an email can also trigger spam filters. Emails that contain large images or attachments, excessive HTML, or text in different colors and fonts are more likely to be flagged as spam. Ensuring that emails are well-formatted, easy to read, and contain relevant information can help to avoid triggering spam filters.

High Email Bounce Rate

A high email bounce rate, which occurs when a large number of emails are undeliverable, can trigger spam filters. This may be due to sending emails to invalid or inactive addresses. Regularly updating and cleaning email lists to ensure that all recipients are active and interested can help prevent high bounce rates and avoid triggering spam filters.

Email Volume and Sending Patterns

Spam filters may also be triggered by the volume and pattern of emails sent by a sender. If a sender suddenly starts sending a large number of emails or frequently changes their sending patterns, spam filters may become suspicious and flag their messages as spam. Establishing consistent sending patterns and managing email volume can help prevent triggering spam filters.

Too Many Images in Emails

If an email contains too many images, this could come off as spammy and cause email systems to send the email to the spam folder.

No Unsubscribe Links in Emails

Typically, valid emails will include unsubscribe links that make it easy for recipients to choose to stop receiving emails from a specific sender. If an email doesn't give recipients this option, email service providers may send it directly to the junk folder.

Poor Spelling and Grammar

Some systems may also send emails to spam if they contain a lot of grammatical mistakes and spelling errors.

Including Too Many Links

Emails may sometimes contain a large number of links that are suspicious and come across as spammy, in which case email systems may mark them as spam.

Requesting a Suspicious Action

If an email asks users to provide sensitive details or perform another suspicious action, service providers may send it to spam.

Spammy Subject Lines

Emails may also have suspicious subject lines that suggest the content contains spam. A questionable subject line alone can cause the email to wind up in spam folders.

The Inclusion of Irrelevant or Suspicious Attachments

If attachments in an email don't seem appropriate or may contain viruses or other malicious content, email systems may consider the email to be spam.

These are simply some of the many potential triggers that can set off a spam filter for email. However, by taking the right steps, you can make sure that your legitimate emails don't get lost in people's spam folders. 

Ways to Avoid Spam Filters

If you want to stop emails from going to junk, there are some best practices to implement in your email marketing efforts. The following are some specific tips to follow if you want to ensure your email goes to the inbox every time.

  1. Create Relevant and Engaging Subject Lines
  2. Personalize Your Emails
  3. Obtain Permission from Recipients
  4. Maintain a Clean Email List
  5. Use a Reputable Email Service Provider
  6. Test Your Emails Before Sending
  7. Comply with Anti-Spam Laws
  8. Monitor and Optimize Email Deliverability
  9. Warm Up Your Email Domain
  10. Personalize Your Email
  11. Proofread Your Email
  12. Clean Up Your Email List Regularly
  13. Avoid Spam Words in Subject Lines
  14. Avoid Unnecessary Attachments in Emails
  15. Use a Reliable Email Service Provider
  16. Email People on Your List Regularly
  17. Give People the Option to Unsubscribe

Create Relevant and Engaging Subject Lines

To avoid spam filters, focus on crafting relevant and engaging subject lines that catch your recipients' attention without misleading or using deceptive tactics. Stay away from all caps, excessive punctuation, or common spam trigger words like "free," "guarantee," or "limited time."

Personalize Your Emails

Make sure you personalize your emails by addressing recipients by their name and tailoring the content to their interests. This shows that you've put effort into understanding and targeting your audience, reducing the likelihood that your email will be flagged as spam.

Obtain Permission from Recipients

Before sending out any marketing emails, obtain explicit permission from recipients. This can be done by using a double opt-in method, which requires users to confirm their email address and consent to receive emails from you. This helps to ensure that your emails are only sent to people who have actively agreed to receive them.

Use a Reputable Email Service Provider

Choose a reputable email service provider (ESP) with a good track record of getting emails delivered to recipients' inboxes. Many ESPs offer tools and best practices to help you create effective email campaigns and avoid spam filters.

Test Your Emails Before Sending

Use a spam testing tool or services like Mail Tester, Send Forensics, or GlockApps to analyze your emails before sending them. These tools will help you identify potential issues that could cause your emails to be flagged as spam and provide suggestions for improving your email content and deliverability.

Comply with Anti-Spam Laws

Ensure that your email campaigns comply with anti-spam laws and regulations, such as the CAN-SPAM Act in the United States, CASL in Canada, and GDPR in Europe. These laws require, among other things, that you include a clear and conspicuous unsubscribe link and your physical address in every marketing email.

Monitor and Optimize Email Deliverability

Regularly monitor your email deliverability metrics, such as open rates, click-through rates, and bounce rates. If you notice a decline in your deliverability, investigate potential issues and make necessary adjustments to improve your email campaign's effectiveness and avoid spam filters.

Warm Up Your Email Domain

Through domain warming, you can build a sending reputation for your email domain or a domain that you haven't previously used to send emails. Warm-up typically entails sending emails from this domain in small quantities before building up to larger volumes. You can do this gradually, increasing the volume of your emails each day, week, or month on a specific schedule.

Personalize Your Email

You should also personalize your email to make it uniquely yours and establish a clear identifier. However, make sure it's devoid of potential spam triggers such as random numbers or other characters that appear suspicious. You can use your name or your company's name, which will help build trust and show that your emails are valid.

Proofread Your Email

Email systems and recipients may find your emails suspicious if they read like the sender didn't care to craft a good email, or if it seems like a computer wrote it. While a small typo may not be enough to warrant sending the email to the spam folder, having multiple avoidable typos and poorly constructed sentences or paragraphs could jeopardize your emails. Your emails should read well and avoid including too many mistakes or poor wording and formatting. 

Before sending your emails, always proofread them to make sure they're of consistently good quality. If you don't feel confident in your proofreading abilities or want a second pair of eyes to look over your email, consult with someone else in your company or another person you trust. You can also use proofreading software to help catch errors.

Clean Up Your Email List Regularly

Spam filters may label your emails spam if you send too many emails to inactive addresses. This means that if you're sending too many emails to abandoned addresses, email systems may interpret your email content as spammy. To avoid this, be sure to remove any addresses connected to email accounts that aren't active. You can do so by checking to see which recipients aren't opening your emails as often. If you find that a recipient hasn't opened your emails in a long time, it may be worth it to remove them from your list. 

However, if you find that your open rate is minimal overall, this could indicate that your email marketing efforts need some modification. By reworking your campaigns, you may find that open rates increase as people find more value in your emails.

Avoid Spam Words in Subject Lines

In the past, you could avoid having emails sent to spam by carefully avoiding specific trigger words in subject lines. However, today, spam filters are considerably more complex and difficult to navigate. This is why it's best to modify your entire subject line to ensure it doesn't sound spammy in any way.

Even reputable brands often have their emails wind up in the spam box because they're poorly worded and suspicious. For example, email subject lines might include too many exclamation points, dollar signs, numbers, or suspicious wording that triggers spam filters. While you can still send emails containing offers in subject lines, practice care when crafting them. Don't overuse specific dollar amounts to attract opens or make your emails sound over-excited.

Spam trigger words

Avoid Unnecessary Attachments in Emails

Never include attachments in your email marketing messages, as they come across as either too personal or generally spammy when coming from a brand. Typically, attachments are reserved for personal correspondence between two individuals, making them best to avoid as much as possible in marketing campaigns.

People are also often suspicious of attachments because they often contain viruses, malware, or other types of malicious software. 

Instead of an attachment, consider including a clear call-to-action (CTA) within your email that directs users to a landing page on your website. From there, people can download an ebook or another piece of content that you want them to download. This will not only help increase downloads, but it will also direct more traffic to your website and help build trust in your brand.

Use a Reliable Email Service Provider

Spam filters also tend to look at IP addresses associated with senders' email addresses. In the process, the filter looks for any complaints regarding these IP addresses. If the system identifies any issues, it will likely flag any email addresses connected to that suspicious IP.

To make sure spam filters don't mistake your email addresses as spam senders in this way, use a reliable email service provider. The right provider will help make sure that spammers don't use their platform, which will help further ensure that your emails aren't mistaken for spam. Additionally, a reputable provider can help you avoid spam filters by preventing common triggers from appearing in your emails, such as suspicious email addresses and neglecting to include a physical address.

Email People on Your List Regularly

Once you build an email list with plenty of subscribers, you need to continually engage with those subscribers. If you don't send emails frequently enough, recipients may eventually forget about your brand and your content, potentially leading them to mark the few emails they receive from you as spam. 

To make sure recipients don't simply toss your emails in the spam or trash folder, connect with them on a regular basis with valuable and compelling content. You can do so weekly or monthly and include enticing offers or helpful content that brings real value with each email. This will help establish your brand as trustworthy and worth engaging with more consistently.

Give People the Option to Unsubscribe

While the last thing you may want to do is get people to unsubscribe to your email list, you should still make it easy for them to do so. Subscribers will be more likely to trust your brand if they see a clear option to unsubscribe, and you'll be able to maintain compliance with the CAN-SPAM Act. You can include a button at the bottom of your email clearly labeled "unsubscribe," and you can place it either in the header or footer of your emails. However, it's best to avoid placing the button in the header to avoid unintentional hits and encourage people to read through the content first.

Take the Right Steps to Avoid the Spam Folder

By implementing certain best practices in your email marketing efforts, you can successfully avoid spam filters and ensure more people see and open your emails. The key is to use the right email service provider and carefully craft your emails to comply with the CAN-SPAM Act and gain the trust of both users and platforms. Taking these and other steps will keep your emails out of the spam box more easily.

If you would like more help engaging with audiences through your marketing efforts, consider integrating Storyly into your campaigns. Through the use of Storyly's App Stories and Web Stories, you can share visuals and messaging that establish a strong connection with audiences. When combined with email campaigns, your customized stories will go a long way in building a relationship with prospective and existing users or customers.


Berkem Peker

Berkem Peker is a growth strategist at Storyly. He holds a bachelor's degree in economics from the Middle East Technical University. He/him specializes in growth frameworks, growth strategy & tactics, user engagement, and user behavior. He enjoys learning new stuff about data analysis, growth hacking, user behavior.

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