When do you need an email spam filter checklist? Imagine… you spend days crafting the PERFECT email. Your copy is clever, your images are eye-catching, and you’ve drafted a subject line that will grab their attention faster than Ryan Gosling’s washboard abs. You send the email to your email list, but no one is opening it. None of your links are clicked. And you get almost zero sales. Why? Where did you go wrong?

Your beautiful email may have ended up in the dreaded spam folder; all your hard work wasted.

Email Spam Filter Checklist

When it comes to email marketing, there are some important rules you have to follow to ensure you end up in the inbox. That’s where our email spam filter checklist comes in handy! Here are 50 of the most common things you’re doing wrong…or need to do better to start making sales with email marketing.

We’ve split our list up into sections to make it easier to diagnose your email spam issue. Enjoy!

Email Copywriting Spam Tips

Is the written content in your email campaign up to snuff? Your copywriting could be triggering spam filters, but this is one of the easiest issues to fix!

1. Did you use any spammy words in your subject line or body?

Gone Phishing? While you shouldn’t alter your copy drastically to avoid using all of these phrases, there are some word combinations that predictably trigger spam filters, like “Save $”. We really hope you aren’t using these lame phrases. But if you are…stop.

2. Does your copy contain relevant SEO keywords?

And are these keywords or keyword phrases incorporated naturally into the email copy? If your email is stuffed with irrelevant keywords, it likely won’t reach your audience. If you aren’t sure which keywords to include, consult your SEO audit for guidance. 

3. Is there a ‘from’ name that is easy to recognize as a “real” person?

Your email campaigns should ideally come from Jenny@yourcompany.com, not hello@yourcompany.com for best email campaign performance.


Why are you yelling at your audience? Settle down. Your copy should be so engaging that it grabs their attention immediately. If it isn’t, no amount of capitalization is going to help. Plus, using all caps triggers spam filters. And makes you seem like you were born in the 1890s…

5. Did you use too many special characters?

Too many exclamation marks, emojis, or dollar signs can send you right to their spam folder…or their trash can. Reel it in or you’ll suffer the consequences.

6. Is your content scannable?

The readability of your email is a factor in how many people actually get to read it. Splitting content up into bite-sized chunks is wise. Use short, concise sentences. Break up text with creative formatting, using subheads and bullet points to draw your reader’s eye where you want it.

7. Did you proof?

You’d be surprised how many email campaigns contain obvious spelling and grammar mistakes. This can be a red flag for spam filters. Plus, it just makes you look like an idiot.

Email Coding and Design Spam Tips

The first thing to take a look at is the email template itself. Is it easy to read? Does it contain the necessary design and accessibility components? Your email may need a bit of work before you can hit that “send” button.

8. Is your copy easy to read?

If you use text and clashing colors that are difficult to read, you might land in the spam folder. Or, your email might just get deleted because it’s illegible.

9. Is there enough space between text and images?

If not, the readability of your email will be impacted. Make sure there is ample space between pictures and copy and also use bullets, short paragraphs, and other visual elements to make your email easier to read. Especially if your audience is elderly or otherwise visually impaired.

10. Are you using unsupported HTML tags and CSS attributes?

Your email may not render correctly in all browsers and on all devices.

11. Are you using JavaScript in your email HTML?

This can sometimes cause issues. Enter at your own risk.

12. Did you use an iframe tag?

Don’t! This usually creates more issues than it solves, in our experience. 

13. Are you using flash?

Don’t do that, either. It’s a pain and pretty much always results in a high number of your sends going to SPAM.

14. Did you fail to include a plain text version of the email?

If the design of your email doesn’t load for some reason, you still want your audience to be able to view a simpler version of your message.

15. Is the ratio of text to images balanced?

Avoid image-only emails or emails that have a ton of images with very little substantiating text. 

16. Is your email over 100 KB?

If not, you may need to compress images and other assets to make sure your email can load quickly. Otherwise, it may be swiftly kicked to spam. Or deleted immediately.

17. Did you include any attachments?

Attachments are a huge red flag for spam filters. Never send a mass email campaign with an attachment.

18. Is your email responsive?

Your email should adapt to whatever device your audience is using—whether that’s their laptop, smartphone, or tablet. Test it on multiple devices before you send your email to customers.

Email Link Spam Tips

While you’ll definitely need to include some links in your email campaigns, they are well-known for triggering spam alerts.

19. Did you test all links in your email?

Dead, broken, or completely irrelevant links are no Bueno. A 404 error will set off alarm bells and screams “spam”.

20. Are there too many links?

We usually suggest no more than 2 links within an email, but this isn’t a hard and fast rule. In general, use as few links as possible.

21. Did you use a tool to shorten your email links?

Shortened emails are often found in spam emails, so always use the full URL without any redirects for best results. No one wants to click on a disguised link and get a virus!

22. Did you include important links and contact info in the header AND footer?

If not, make sure important info appears in both places so your audience doesn’t have to hunt to find it.

Email List Spam Tips

The quality of your email list also impacts your spam risk. Great list = more engagement from readers and a healthy email send reputation.

23. Did you buy your email list?

If you paid for it, you’ll have a higher chance of landing in the spam folder. If you’re going through the trouble of reading this email spam filter checklist, you probably also have time to add a simple popup to your website to gather emails! This article has a great example.

24. Have you asked your email recipients to opt-in?

A good email list consists of people who already know you (or at least people who want to know you). They’ve opted-in to your emails (some may have double-opted in, even better). They recognize your domain and add you to their trusted sender’s list. Check out our blog post on how to grow your email list if you’re struggling!

25. Are people on your list marking your emails as spam?

If you’re seeing a huge dip in open rates and other important statistics, you might have been flagged as a spammer. Sometimes if enough people flag you, you’ll get a notification. You may even have your email account temporarily suspended.

26. Are people blocking your emails?

ISP’s sometimes block emails automatically, but people can also manually block your email address. If they do, you’re doing something VERY wrong.

27. Do you have a way for people to reply to your emails?

No-reply emails are sometimes necessary, but they often land in the spam pile.

28. Do you clean your email list regularly? 

Are your emails bouncing? At least once each quarter, remove any emails from your list that are obviously dead, incorrect, or aren’t engaging with your campaigns. The fewer emails you send from your chosen email address, the better. And you want the emails you do send to be opened and engaged with regularly.

Content Strategy Spam Tips

Plan ahead and pay attention to performance analytics to improve email campaign success!

29. Have similar emails been marked as spam by users in the past?

Then you need to revisit your strategy. Don’t repeat the same mistakes over with this campaign! Each time you run a new campaign, refer back to this emails pam filter checklist to make sure you’re using best practices.

30. Are your campaigns targeted?

Segment your list and target different audiences for different campaigns. Personalized, customized email campaigns always perform better.

31. Are you sending emails at the best days/times to reach your audience?

Sending at 3 a.m. isn’t always the best option, even if that’s when you finish your email template. Who else emails people at 3 a.m.? Spammers. That’s who.

32. Do you send emails on a consistent schedule?

The best way to build your reputation is to follow a schedule and build trust with your readers. Sending emails regularly (like every week or once a month) is better than sending 3 emails in a short time period. This is why planning your email campaign strategy with an agency like Witty Kitty is an important step to take once a quarter or even yearly.

33. Are you sending too many emails?

No matter how awesome your product or service, it gets very annoying to hear from your brand multiple times a day. We suggest sending, at maximum, 2 emails a week. Definitely add this guideline to your email spam filter checklist if you implement nothing else!

34. Are you sending only sales emails?

Everyone loves sales, special offers, and new product announcements. In moderation. Make sure that you’re also sending your audience email campaigns that contain newsletter content and other creative, educational resources that might help your readers. Give more value to your email list—don’t just bombard them with promotion after promotion.

Technical and Accessibility Email Spam Tips

Some of these tech-heavy tips even make our heads spin, but they’re important nonetheless!  While most of us think about the things we can see (the email, our list, etc), many forget about the backend processes. Make sure your website domain and IP are set up for success to predictably stay in their inbox. And make sure your emails are accessible for those who may be using text-to-speech!

35. Do all images have alt-text?

They should. This makes your email more accessible so it is more likely to evade that spam filter.

36. Where was your email sent?

The location of the IP address that your email is sent from sometimes impacts deliverability, so we suggest that you avoid using a third party to send mass emails from abroad. Stick to smaller sends with a personalized message if you choose to go this route. 

37. Is it a free email address?

Use a verified business email instead.

38. Do you have an unsubscribe link in the header and footer?

You have to have one. It’s not optional and it’s also just common courtesy. If your email campaigns are good, your audience won’t unsubscribe!

39. Do you have a physical address in the footer?

You ideally should. This helps inspire trust and lets your audience (and their spam filter) know you are a legit business.

40. Do you have an established domain?

Messages from a brand new domain are more likely to be flagged as spam.

41. Are you sending lots of emails at once from a new domain?

Your domain could be penalized or your email address suspended. Especially if this factor is combined with other spam threats from this list.

42. Do you regularly check your “reply to” email inbox?

Always do your best to quickly respond to email messages.

43. Has your domain ever had a phishing violation?

If so, you’re skating on thin ice. Be careful not to continue to trigger spam warnings. If you aren’t sure how to fix the situation, it might be time to hire a professional. Your domain’s reputation plays a big part in whether your emails get delivered. Ensuring your domain has a clean rep is one of the easiest ways to avoid ending up in the spam folder.

44. Is your DMARC properly configured?

Your Domain-based Message Authentication, Reporting, and Conformance inform email services of what to do when they receive a message from you that they can’t authenticate. 

45. Do you have an SPF record?

A Sender Policy Framework allows the domain owner to determine which IP addresses can send emails for the domain. This is always best practice and prevents unauthorized sends that could damage your reputation.

46. Do you have a DKIM record?

Your Domain Keys Identified Mail adds a digital signature to emails which allows the receiving email service to verify authenticity. This is a good thing!

47. Do you frequently change IP addresses?

New IPs are suspicious and often end up flagged.

48. Does your IP have a Return Path Certificate?

Get certified as a trusted sender and you’re more likely to have your emails seen.

49. Have you tested your email using a spam Checker?

Once you’ve gone through our email spam filter checklist, you should test your email and get a spam score. A spam score ranges from 0-10.  We recommend shooting for a three or below for the best deliverability. 

If You Think You’re Ready To Hit Send…

Not so fast!

50. Is your email the absolute best it can be?

We hope this has helped you figure out why your emails are hitting the SPAM filter, but if you still need help perfecting your email strategy, let us know! We can design professional-looking emails and get your campaign successfully delivered! Just drop us a line.