10 Tips to Keep Email Out of the Spam Folder

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At SendGrid we are very serious about email deliverability. We live and breathe it each day. Similar to how Google keeps adjusting its search algorithm to provide the best results, we must also regularly adjust to ensure your non-spam email gets delivered. In this post we offer advice to help you make sure that your emails get delivered. Of course, the very best advice we can offer is to use SendGrid.

Photo Credit – nobody loves spam, except possibly this person

 For additional information, check out our Tips & Tricks to Stay Out of the Spam Folder Guide.



1. Be Compliant with the CAN-SPAM Act

If you are sending “any electronic mail message, the primary purpose of which is the commercial advertisement or promotion of a commercial product or service,” then you must comply with the following 7 main requirements (or face penalties up to $16,000) [5]:

  1. Don’t use false or misleading header information
  2. Don’t use deceptive subject lines
  3. Identify the message as an ad
  4. Tell recipients where you’re located
  5. Tell recipients how to opt-out of receiving future email from you
  6. Honor opt-out requests promptly
  7. Monitor what others are doing on your behalf

If your email contains only transactional emails or relationship content, then you are exempt from these rules; however, you must still not include false or misleading routing information.

2. Avoid Spam Trigger Words and Phishing Phrases

Unfortunately, there is no complete list of spam trigger words. Further, it is not always the case that your email will end up in the spam filter simply by using a so-called trigger word.

The key thing to remember, is that a spam filter is trying to remove commercial advertisements and promotions. So generally, words that are common in such emails should be avoided or used sparingly. That said, take a look at these 100 Spam Trigger Words & Phrases to Avoid.

Phishing emails are designed to steal your identity by getting you to click on a fraudulent link. The most common method is for the email to be disguised as a legitimate email from a service you trust, such as your bank or a website you frequent. Thus, you want to avoid using phrases that are common to phishing attacks. At 24HourSupport.com you will find a short list of common phishing phrases along with references for further investigation.

3. Include a Text Version of Your Email if You Are Sending HTML Emails

This is a common, and easily preventable, cause for landing in the spam folder. Not only is this a good practice for avoiding a spam filter, but it also covers you in the case where the recipient can not view HTML emails.

4. Use Permission Marketing Techniques

Seth Godin coined the phrase “Permission Marketing,” and offers his thoughts here. There you will find sound advice on the ideas behind getting your customers or potential customers to give you the permission to email. Take it a step further at the point of subscription and ask to be placed on their white list.

5. Use Spam Checkers Before Sending Your Emails

Before sending emails out to your entire list, its worth the time to utilize a spam checking service.

MailingCheck.com offers a free downloadable tool for Windows that uses SpamAssassin to check. If you prefer to avoid downloading any software, you can send email to the IsNotSpam.com service and they will also check a few other items important to email deliverability. Alternatively, ProgrammersHeaven.com uses a form-based solution to test your emails.

6. Get Off Blacklists

If your email server is on a blacklist, it becomes extremely difficult to reliably send email, especially to new people on your lists.

The first step is to check if your email server is on a blacklist, following are a few free services:

If you find that you are on a blacklist, you will need to follow up with the website that has added you to their blacklist. That information is provided by the tools listed above.

7. Maintain a Good Text to Image Ratio

It is usually best to not include images at all; however, if you must include images, here are some tips:

  • Do not send any image-only emails
  • We suggest that for every graphic, include at least two lines of text
  • Optimize your images the best you can
  • Use well formed HTML for email

8. Avoid Spam Traps

Spam Traps are email addresses that are flagged by ISPs as being no longer used by a human, so it then stands to reason that there could have been no opt-in. To avoid including a Spam Trap email in your mailing list, use a opt-in process and do not buy lists from email brokers.

9. Avoid Large Attachments and Certain Attachment Types

In general, .jpg, .gif, .png and .pdf attachments are safe to send, provided you include some content in the email as well. However, executable attachments such as .exe, .zip, .swf, etc. should be avoided entirely. Generally, you should not send attachments to people on your list that are not expecting them.

If you need to email a large attachment or an attachment type that usually can be flagged as spam or trigger virus scanners, we recommend a service such as DropBox.com. If the attachment contains sensitive data, you may consider using your company’s secure FTP server.

10. Make Sure Your DKIM, SPF, Sender-ID and Domain Keys Are Setup Properly

You will want to make sure your email server supports these protocols (DKIM, SPF, Sender-ID and Domain Keys) and that they are properly implemented.

This alphabet soup helps ISPs determine the authenticity of your email from a technical perspective. To make sure yours are setup properly try using IsNotSpam.com‘s checking service.

If you want to dig deeper, here are the definitions:

Bonus Tip: Use a Email Delivery Service

If this whole process seems daunting and you would rather just focus on your company, we understand! Providing the best email deliverability is the reason we exist. You can either use our SMTP service to get started in minutes or you can utilize our REST API for maximum customization. If you’re just not sure, try us out for free.

Do you have any spam avoidance tips? Join the conversation with us here on the blog, on Twitter or on Facebook. We love feedback!

This post was updated and republished from 8/18/2010.

Elmer Thomas is SendGrid's Hacker in Residence. His mission is to help SendGrid live up to its slogan: "Email Delivery. Simplified" by improving the lives of developers, both internally and externally. Via all sorts of hackery, of course. Follow his exploits on Twitter and GitHub.

Elmer Thomas on Twitter

24 thoughts on “10 Tips to Keep Email Out of the Spam Folder

  1. SendGrid team, that's a very comprehensive list of email deliverability tips. I would also add that any company – large or small – can check their Sender Score for free at http://www.senderscore.org. A Sender Score is a like a credit score for email deliverability. If you check your Sender Score, you'll have a good benchmark to start your work on deliverability. If you know what your email reputation currently is, you'll know how much work you've got to do in improving your reputation – and ultimately getting more of your emails delivered to consumers' inboxes.

    • Thanks Tom! I appreciate your added wisdom and the time you took to share with us, I'm sure our readers will benefit.

  2. Great Recommendations! Thank you for the time to research and compile these suggestions. I have had a problem on sending a jpg file as an attachment or embedded in the message. This particular file would automatically get caught by Spam Filters at the server level… I sent it to myself and it would show up in my own spam filter on my IPS' webmail server but I could never download it to my PC with my Windows Mail. All recipients never received my email… so I knew something was amiss. I tested with another jpg file and it when through with no problem. So I opened the jpeg in Photoshop and selected the image and cut and pasted it into a blank photoshop file and saved it as a new jpg file… then attached that file of the same image instead of the original jpg. It was emailed with no problem. All recipients received the email and the revised jpg. So it seems the Spam filters on the server level examines the jpg data of a jpg file and somehow makes a decision that it could be spam or not.

  3. Great article. I have to send important e-mails frequently and I am always scared about them ending up in recipient's the junk folder. Facebook messages all the way :D Anyways great article. Thanks for sharing.

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  5. Help, all of a sudden my facebook notifications that used to go to my inbox email folder on my computer are going to junk mail. This has been happening for about 3 weeks. I went in and told it to unblock and clicked not junk but they still fly into the junk mail folder. Anybody else had this problem?

    • @Ellen That sounds like it might be an issue with your email client. Try creating a filter to route those notification emails to a folder instead of just clicking on "not junk".

  6. Thanks for the article and great resources. I've always been wondering how to reduce the risk of my emails being filtered by spam filters. Your article provides many great methods that have helped me manage my own mailing list and email campaigns.

    I would also like to share another service that I came across recently: http://www.sendalysis.com. It provides a comprehensive spam analysis report of your email and how to improve it for better delivery results. The great thing is that is also provides information about which ISPs are likely to block your email. If you know a certain ISP is likely to block your email, can fix it before sending it to your mailing list.

  7. Thanks for this. But my question to you is: Why does all the email I send to myself, end up in JUNK. Whenever i include a cc to myself of a letter i'm sending to someone else, my copy arrives as junk. Thanks!

  8. The great thing is that is also provides information about which ISPs are likely to block your email. If you know a certain ISP is likely to block your email, can fix it before sending it to your mailing list. Thanks for sharing this great info here.

  9. I think I just found my answer from your post. I have started an online business and am sending out important order emails to my customers and was wondering why they they never get it. It always ends up in their junk folder. I definitely think my problem is that I am not sending them a text version. If not that, then I will try all the other tips you have suggested. Many thanks.

  10. Lol, I was trying to find out why my email is full of spam. Even the emails that my friends send me land on spam box. Using Windows live. And I now get it. Thank you for the information.

    • Good question. If you throttle your send on your end prior to queuing up your mail to SendGrid, then yes, this could help your deliverability. Throttling your mail will prevent you from exceeding the maximum connection limits that the ISPs have. If you exceed this limit, your risk becoming blocked or deferred by the ISP. –Jillian @ SendGrid

    • Yes. Every time you send out an email there is an accumulative effect on your sender reputation. Whether that effect is negative or positive will depend on how closely you follow the above tips.

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