How Your Emails can end up in a Spam Folder


We sometimes get asked why email sent from inside the system goes to a contact's spam folder. The reality is that email sent from anywhere can easily end up a spam folder if certain best practices are not followed. Below are a few popular articles that may help further explain.

Reading these articles can give you great insights as to how to minimize the odds of getting up in someone's spam folder when sending emails.



 (Article #1)


Does the content of my email matter for deliverability?


Absolutely. Ideally, you send email that people want. That's over half the battle. In addition, you should make your content interesting and relevant to the recipient.

There are a few things to keep in mind about your email content. First, we suggest that you set up a test mailbox at Mailgun and enable our spam filters to receive a Spamicity score to test how your content is being judged by spam filters. Here are some other things to consider:

Personalize your emails. Make sure to include the recipient's address in the To: field and include his/her name in the greeting.

It is best to send multi-part emails using both text and HTML or text only. Sending HTML only email is not well received by ESPs. Also, remember that ESPs generally block images by default so HTML only will not look very good unless users are proactive about enabling images.

  • Test how your html email looks across all email clients and browsers. Litmus and Return Path have tools to do this.
  • Make your content relevant and targeted to the recipient. There are even tools like Movable Ink that let you dynamically update your content after it is delivered.
  • The higher the text to link and text to image ratios, the better. Too many links and images trigger spam flags at ESPs.
  • Misspellings, spammy words (buy now!, Free!) are big spam flags, as are ALL CAPS AND EXCLAMATION MARKS!!!!!!!!!!!!!
  • The from field in your emails should match the domain you are sending from. Hotmail is particularly focused on this.
  • Make sure you are using unsubscribe links and headers in your emails. Many ESPs (particularly Hotmail) pay attention to this and if they are not there, you are likely to get filtered. You can always use Mailgun's auto unsubscribe handling if you don't want to deal with this on your end.
  • Include your physical mailing address. CAN-SPAM requires an unsubscribe link and a physical mailing list. It is also a good idea to provide a link to your privacy policy.
  • Gmail pays particularly close attention to Message ID and Received headers. Message IDs that are formed incorrectly (without brackets and with wrong domain after @) can make Gmail think you are a spammer. The simplest way to create the right Message ID is to not set Message ID at all. Then Mailgun will create a perfect Message ID for you. Also, if you use the HTTP API, Mailgun will deal with all of this for you.
  • Links should include the domain that is sending the email. Also, popular url shorteners can be a bad idea because they are frequently used by spammers.
  • Long links may cause bounces. Some ESPs will block emails with links (or any consecutive text) longer than 99 characters.

A/B test your emails to optimize recipient engagement. Subject lines are particularly important. You can use Mailgun's tagging and tracking statistics in order to measure A/B testing and improve your content.



(Article #2) 


Why Is My Email Going to The Spam Folder? How To Improve Email Delivery


With any email service & any set of contacts you will always have some mail end up in the spam folder. Every receiving ISP is using different spam filtering techniques and some ISP's utilize some pretty crazy  ideas to combat spam. So you will undoubtedly have some mail filtered at some point during sending email campaigns.

The good news is that it is not something you should dread or worry about. By following some pretty simple concepts you can dramatically reduce the chance of email being filtered.


Things you can do to improve your email delivery:


1. Don't use your email address for the from email address.
If you send a email that is from your email (let's say and you send it to a contact with the email ( it will most certainly be marked as spam as the from and the to is the same.


2. Pay attention to the spam filter testing before sending.
This is an option on the summary step of create campaign. It will let you know if it spots any major issues with your email that could affect delivery.


3. Don't send a single graphic/image
Sending an email that only contains a graphic is a sure-fire way to have delivery issues. You should take the time to design an email with text and graphics. Not just a single image.


4. Don't use a free email address as your from email
Instead of using your free/personal email address such as or you should use an email address for the company or organization for which you are sending email.


5. Test different subjects & email contents
Content does play a major role in filtering email. Avoid using all caps, spammy sounding content, etc… By testing different subjects and email contents you can test responses & delivery.


6. Pay attention to your links in your email
Spam filters check the URLS that you are linking to. If you link to a domain that has a poor reputation you will be penalized. Additionally you should avoid linking to URL's that contain folders with 1-2 characters (such as or as some filters will count that as a negative thing.


7. Don't include links that use link shortening services
Your links should be full links to the real URL. You could experience delivery issues using shortened links from link shortening services.


8. Take the time to code your HTML correctly
Improper HTML tags, broken tags, etc.. could reduce your email delivery.


9. Remove inactive contacts
Delete your old & inactive contacts. Contact engagement plays a big role in email delivery. By focusing on your active contacts you can increase your overall delivery.

  1. Send using a consistent from email address
    We do not suggest changing your from details often. Keeping it consistent can help build your reputation.
  2. Never include Javascript, form code, or video within your email
    This is an absolute way to get filtered. If you wish to have video checkout this article.
  3. Avoid copying anything directly from Microsoft Word, Excel, Powerpoint, etc..
    When you paste content directly from these applications additional characters (that you do not want) will be automatically added.
  4. Don't test using the same phrase as your subject and email contents. If you send an email with a very similar subject and message body it will likely be filtered as spam. (An example would be having the subject set to "this is a test" with the body set to "this is a test".)

Be sure to keep in mind that your primary focus should be on maintaining a healthy list of contacts, sending content that they truly want, engaging your contacts, and encouraging them to interact with your campaign. If you keep your focus on these items great delivery will follow.


How To Write Subject Lines


The subject line of your email is the hook that draws your subscriber to  open your email. The subject line as well as the From line are the single most important factors when it comes to whether or not a subscriber reports you as spam. 7 in 10 email recipients judge the From and Subject lines when determining whether they want to mark you as spam. For something so important, many people do not pay enough attention to the subject line. Certainly not enough attention to split test it to see which subject lines will give them the best response. Often times the subject line is written thoughtlessly and without testing before the email is sent.


It's About the Content


The content of the email should guide the subject that you give it. For that reason you might want to wait to do your subject line last. The subject line may appear to be an ideal play to let your creative juices flow. After all, you want to grab your subscriber's attention, don't you? When it comes to subject lines it's better to be simple and honest rather than catchy and misleading. There's nothing wrong with a subject line that looks like this: [Your Company] Monthly Newsletter. On the other hand think of the spam you've gotten recently. They're dramatic and give the subscriber a false sense of expectation: YOU'LL NEVER FIND A DEAL LIKE THIS ONE. Your subject line creates an expectation for your subscriber about what content they should expect to receive when they open up your email. Subscribers are leery of anything that closely resembles spam and telling them they will never receive a deal like this one not only sets up a false sense of expectation, but is likely illegal. 

Your subject line matches the content of your mailing. The more direct your subject line is the more likely your subscriber is to open your mailing. You can be direct and still write an engaging subject line that gets your subscriber's attention. You just have to let the substance inside your mailing be your guide. Ask yourself what's in it for your subscriber?  If you do not have anything interesting to offer your subscriber by opening your mailing then you shouldn't be sending it to them. It's better to hold off on mailing to them until you can offer them something that would interest them. That way you do not lose them as a subscriber.

What you do not want to do with your subject line is make it sound too much like a sales pitch. Every possible cliche for trying to grab someone's attention has already been exploited by spammers. People prefer authenticity over spin. If you make your subject line sound too much like a sales pitch or come off as being too needy they will assume you are being misleading.  We talked about some of the things you want to avoid with subject lines when we discussed effective email marketing writing. Avoid using $ signs, all caps, excessive punctuation, exclamation points, % off, reminder, free, and help.  Stay away from anything that resembles anything in your spam box.

Even though you want to get your subscriber's attention it's better to be a little boring than too pushy. If the subject line even resembles something your subscriber has seen in spam then this will turn them off and they will never open your mailing.  Worse they will report you as spam and this will jeopardize your ability to even deliver your mailings in the future. Be simple, direct, and modest in your approach. If the substance in your newsletter makes it worth opening then the subject line should write itself. 


How Long Should Your Subject Line Be?


The general consensus is that short and sweet works best. Most email clients can display 50 characters or less. According to Return Path subject lines with 49 or fewer characters had open rates 12.5 percent higher than those with 50 or more characters. Click-through rates for subject lines with 49 or fewer characters were 75 percent higher than those with 50 or more characters. More and more people are checking their email using smart phones and the like so as few as 20 characters may be more effective in order for proper display. 


The Forgotten Art of Testing


Because Subject Lines are such an important indicator of whether or not a mailing is likely to be open split testing a campaign to see which type of subject line gets a better response is strongly encouraged. Find two or more of your strongest subject lines and see which one of them gets the best results. If you are using email marketing software there is even a winner feature that will determine which of your subjects are generating the best response and send the email out to the rest of the subscribers using the most effective subject line.  You may also want to see how the subject line appears in various email clients or even on an iPhone or a Blackberry to make sure it displays properly.



(Article #3) 


How to increase e-mail delivery rates, part 1: Avoiding spam filters


One of the most frequent questions we hear from people who are looking into or using Email Marketing is how to ensure that their e-mail reaches its intended audience and gets looked at. In this post and the next post, we will get a solid introductory grasp of the subject of email deliverability.

The first thing to look at, obviously, is spam filtration. If your message is filtered as spam, it will probably never be read, so preventative measures are definitely in order. The single most important thing you can do to make sure your messages don't get marked as spam is also the simplest and most logical: don't send spam! Send quality content at reasonable intervals. If the message you're sending contain a sufficient quantity and variety of original text, you're not likely to have to worry about trying to do anything sneaky to get past the spam filters.

You can also improve the delivery rate of your messages by improving the  relationship between your own server and those of the receiving servers by setting up a Sender Policy Framework (SPF), which reduces the chances that spammers will be able to use your domain name by specifying which computers are allowed to send e-mail from your domain.

A second line of defense for avoiding spam filtration is to run your message through some spam filters before you send it out to your subscribers. If you're using ActiveCampaign Email Marketing, you can use our EmailCheck add-on to run your message through an up-to-date copy of SpamAssassin that we maintain on our servers. SpamAssassin is the most popular spam filter on privately maintained servers, and the add-on will give you a list of any specific problems it finds so that you can correct them before sending the message. You can also test your messages against the major webmail services spam filters by simply sending a copy of the message to your own accounts on those services. It's a good idea to maintain a test mailing list consisting of all of your own e-mail addresses and those of colleagues working with you on your marketing efforts, and to send a copy of each message to this list prior to sending to your main list. That way you can anticipate and correct most problems before they happen.

The third way to prevent your messages from being filtered as spam is to prevent your subscribers from marking your messages as spam. This means  always enabling double opt-in features in your mailing list management software. It may seem like you'll be losing a few subscribers who can't be bothered to confirm their subscription, but in the long run those subscribers probably weren't that interested in your mailing list anyway, and likely wouldn't have remembered signing up in the first place. That translates into more spam complaints.



(Article #4) 


Where Does Email Go When It Isn't Delivered? Part 2


A sender's reputation can follow not only an IP address but a brand and a sending domain. A holistic approach is necessary when considering a sender's reputation as no one factor alone determines what that reputation is. Reputation can be broadly defined as the opinion of a community toward an object. Knowing what the community looks for when determining a reputation will allow you to maximize your delivery rates.

Spam traps

We first eluded to spam traps when we discussed Paid Subscriber Lists. A spam trap is an email address that appears to be valid but is in fact used by ISPs to catch spammers. You will sometimes hear these referred to as honey pots. Spammers use harvesting programs which scan millions of web pages looking for email addresses. These email addresses may come from old email addresses which are recycled by ISPs in order to catch commercial emailers that use old, rented, or paid subscriber lists.  Some sites bury email addresses in their source code so that they are picked up by harvesting programs.  The company where the email originated is then alerted to any incoming emails that go to that address at which time they contact your web host and file a spam complaint. Spam traps are bad news. Its been reported that your delivery rate can drop as many as 20 points drop with one spam trap hit. Spam traps are one of many factors that ISPs look at when calculating your sender reputation. Not only is your deliverability affected but they can result in temporary or long term blocks.

Good list maintenance is necessary for avoiding spam traps. Here are some things you will need to avoid:

  • Poor List Sources -  This includes avoiding paid subscriber lists as mentioned previously
  • List Poisoning - Using confirmation Opt-In mailings will reduce the chances that you will receive invalid email addresses
  • List Aging -  Because spam traps are often used by recycling old email addresses use bounce management to remove any old email addresses and also remove any inactive addresses from your list.

Sender Authentication

This is used to prevent domain forgery and spoofing and provides a framework for helping ISPs to distinguish between legitimate email senders and spammers. ISPs Identifying and verifying a claimed domain name has been authenticated or authorized for sending from a MTA makes it possible to treat suspected forgeries with suspicion, reject known forgeries, and block email addresses from known spamming domains.

  • Sender Policy Framework (SPF) - a record that allows you to determine which computers can send emails on behalf of your domain. Adding an SPF record to your domain name's TXT entry, while not required, can help improve email delivery rates by reducing the chance that the emails you send will be seen as spam.  It can also help prevent others from sending spam and using your domain name. This is used by Bellsouth, AOL, Gmail, and MSN/Hotmail.
  • Sender ID - is very similar to SPF record except this extends the verification process to include the purported responsible address included in the header. Used by MSN/Hotmail
  • Domain Keys - an authentication standard that is designed to verify the DNS domain of email sender and the message integrity.  All outgoing emails are digitally signed with a private encryption key to match a public key that is published in the sender's DNS record.   Used by Gmail, Yahoo, SBCGlobal, British Telecom, Rogers Cable, Rocket Mail, etc.
  • DKIM - an enhanced authentication standard that allows a person to verify that a message comes from the domain that it claims that it came from.

Getting Technical

Your system admin should be able to assist you with ensuring that the following technical configurations are in line as they can improve or harm your sender reputation.

  • IP Address because email originates from this address you need to establish a low history of spam complaints, spam-trap hits, and low bounce rates in order to have a positive reputation that will affect your long term deliverability. If you wish to qualify for whitelists, feedback loops, and reputation services, your IP address must have low spam complaints, unsubscribe management, and proper setup for the domain associated with it.
  • Sending Domain or Subdomain Domain registration and domain age are two factors for establishing a positive reputation.  Newly registered domains are regarded with suspicion as spammers often hop from domain to domain.If a sending domain has a bad online reputation it will result in low deliverability rates.
  • RFC Compliance these are information documents used as governing standards for internet traffic.   RFC 2821: Simple Mail Transfer Protocol and RFC 282: Internet Message Formatare relate to email reputation.
  • Reverse DNS used to identify the domain name associated with an IP address.  The IP address is the only data that can not be forged and not having this enabled is in violation of RFC standards and a requirement for many ISPs.  If this is not enabled or is configured improperly you must immediately contact your server admin.
  • Bounce Management An email address is considered dead and should be removed from your list if it bounces 3 consecutive times or if the time between the most recent consecutive delivery rejection is in excess of 15 days.

Where to Go From Here

The final way to improve your deliverability is to get certified or accredited by a reputable organization. There are three different types of ways to get yourself certified!  The first gets your emails automatically whitelisted or delivered to ISPs and companies that are working with the relevant program. Another audits your email practices so that you can display a seal of approval next to your sign up form. Another allows you to display an icon next to your email in your inbox that indicates that your email passed a quality test.  We will focus on whitelisting programs here:

  • Goodmail Systems -  ISPs supporting this program ensure delivery with a certified icon attached.  This accreditation is supported by Yahoo and AOL.
  • Sender Score - Acceptance in this program puts you on the whitelist that includes 240 email address as well as MSN/Hotmail and Roadrunner.
  • SuretyMail - While not technically a whitelist a large number of ISPs, spam filters, and mail servers take this accreditation into account when making delivery decisions.  Senders with this accreditation will see improved delivery.


© 2005 - 2024 ProProfs
add chat to your website