Why is My Email Going to the Spam Folder?


No one wants their email to hit the spam folder, and while many mechanisms that determine when an email ends up in spam are opaque to marketers, Sendlane is here to help you avoid the spam folder! Read on to learn about the most common reasons emails end up in spam, how Sendlane protects you, and what you can do to avoid the spam folder.

In This Guide

There are 4 main factors in determining whether an email hits the inbox or the spam folder:

  1. Content
  2. Subject Lines
  3. Links
  4. Email Address Issues


Pre-Written Templates

When email service providers (ESPs) see many different senders trying to deliver the exact same content, their algorithms detect the copied content and will stop inboxing emails that use it. 

Whenever you use pre-existing content, you need to rework it before sending it so that you can be sure it is unique. You can use pre-existing content as a guide, but make the emails your own to help increase your deliverability.

Email "Curse Words"

In addition to crawling for duplicate content, email providers also have filters on specific words that are frequently seen in spam emails.

For a more detailed (but not exhaustive) list of words you should avoid in your emails, check out the Email Curse Word Database. While you are following this list, remember: your goal is to always stand out!

Please Note

While it’s true that spam filters look specifically for these words, the chances of your messages being marked as spam will differ based on your own sending reputation. Maintaining your sender reputation with a hygienic and engaged list is key to being able to use these words more freely!

Imagery, Formatting, and Special Characters

Adding excessive text formatting (like bold, italics, different font sizes or colors) and special characters or punctuation (like !!, $$, ... or ==>) is a huge red flag for spam filters.

Stock images that are available online for anyone to use are another great way to get flagged for duplicate content. 

Start off sending simple messages with fewer images and text modifications. And be sure to use original images (like your own logo and product photos) for best results.

Please Note

Once you've built up your sender reputation with a few sends that engage well, your content will start to inbox more consistently and you can start sending more "fancy" messages.

Subject Lines

Subject lines can actually be more important than the body of your messages!

When you think about grabbing your audience’s attention, you should always go for shorter and more compelling sentences. Be clever and grab attention with just 5 words or so.

Also, it's important to be honest. Your subject line must  directly relate to the content that you're sending within the body of your message, and avoid using anything that could potentially be deceptive (especially like "RE:" or referencing order numbers since marketing emails aren't transactional).

Avoiding words in the Email Curse Word Database is important when crafting subject lines as well.


Masking Links

You should always avoid displaying a raw link. More people click on masked links than raw links, so be sure to mask your links in text or in a button! 

Follow our guide here to learn more about how to mask your links.

Email Address Issues

As an email marketer, you need to establish where you're sending from.  Building up a healthy sender reputation is very important!

According to DMARC’s most recent legislation, in order to send marketing emails, you are required to have your own domain-based email address, backed by a corporate website. DMARC is the email validation system that helps prevent email abuse including spam, phishing, fraud and other email-based scams. 

If your business domain is brand new, your domain is essentially a blank slate. Similar to how a credit score starts off very low before you've built up credit, you improve your rating by showcasing responsible spending. You also need to build up your domain/sender reputation with responsible  sending!

When your "from" email address is unknown to Gmail and other providers, algorithms set up to detect spam will be monitoring the address, subject line, and content of your emails very closely. 

Please Note

If you have multiple Spam complaints against your domain or a poor sender reputation, you will have a hard time inboxing any of your campaigns - regardless of the content. 

Testing Your Emails

Testing is one of the most important parts of the email marketing process. It helps ensure that the messages you send will actually be delivered to your recipients - and that everything looks the way you want it to.

If you don’t test, your emails may end up in your contacts' spam folders without you ever knowing it!

How to Test

  1. Start by making sure that your “from” email address is not in your address book or allowed/approved list (this will skew your test)
  2. Create new "test email" accounts in Gmail and Yahoo (these are widely used services) to send test emails to
  3. Build your email (subject line, content, links, etc.)
  4. Once your email is ready, click the "..." and then select Send Test to send yourself a copy
  5. Check to see where your test email lands
    • If you find it in your inbox - great! You can stop testing and send away!
    • If you find it in your spam folder or it never arrives, it's time to revisit the list of Spam factors one-by-one
  6. Revisit your content
    • If you started from a template, rework the text so it feels more unique
    • Check to be sure you're not using anything listed in the curse word database
    • Simplify your formatting and remove special characters or images
  7. Once you've made changes, repeat Step 4. 
    • If your new version still lands in spam or never arrives, keep testing:
  8. Tweak your subject line, then send another test
  9. Check your links and send a new test
  10. Swap out the email address in your sender profile and send another test

Testing Outside of Sendlane

The testing functionality inside Sendlane works like a charm, but it'll never hurt to implement a bit more testing! Luckily, there are other services out there whose purpose is to ensure your Email Marketing is efficient and problem-free before you send. 

Here are a few platforms that offer Inbox Placement Testing:


Moving forward, keep in mind that deliverability depends on  many different factors including everything listed above, as well as your contact's email service provider. Each ESP ultimately has their own unique spam filters and algorithms to parse the content of incoming emails. Because of that, delivering consistently to some email domains can bit more difficult. ESPs, like Microsoft and Gmail, have harsher spam filters and can send emails to other inbox folders.

That said, Sendlane offers world-class deliverability, especially to Gmail-based accounts which is what the majority of people use today! 

Additional Sendlane Resources


Content Focus: Pre-Written Templates, Email "Curse Words", Imagery, Formatting and Special Characters

Subject Lines: Avoid words listed in the Email Curse Word Database

Masking Links: Follow our guide here

Email Address Issues: Build a healthy sender reputation with your own domain-based email address

Testing Your Emails: Unique "From" Email Address → Create New "Test Email" Accounts → Build Email → Click (...) → Send A Test Email → Check to see where your Test Email lands (If it lands in Inbox, stop - If it lands in Spam, keep going) →  Revisit Content and Revise (Make tweaks to Subject Line, Links, Sender Profile) → Send Another Test Email → Repeat these steps until Email lands properly

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