Nothing is for sale here. Freewill tips keep the site running. Want to help? → Tip via Paypal

Stop Your Emails from Being Flagged as Spam

Why Does Email Get Flagged as Spam

An email service provider (ESP) using algorithms to flag spam, much like a search engine uses algorithms to determine the best search results. There are multiple factors that are at play.

Also like a search engine, ESPs closely guard the criteria that factors into their algorithms. They don't want spammers to know how to get around their attempts to stop them.

There are something we can be reasonably sure of, however.

Known Spam Triggers

1. Blacklists. ESPs (and many ISPs) keep an internal blacklist of domains and companies whose emal they will automatically block. They also use shared national and international lists. If you get placed on a blacklist you'll have rebuild your email marketing from scratch. These blacklists are for serious spam offenders. We're talking those who send out millions of emails. It's not not a big concern for most of us.
   
   The opposite of a blacklist is a white list. White lists are kept on the individual ESP level. These are lists of domains or senders whose emails are automatically approved for delivery. If you can get on a white list you won't have to worry about deliverability with that ESP.
2. Sender Reputation. Your sender reputation is a score assigned to your sending IP or source. If you are using a third party email platform such as Aweber or Get Response, they constantly work with large ISPs to help ensure deliverability.
   
   It's important to select a service that has a high sender reputation. Many provide "spam grades" for your email before you send it so you can make corrections to problems that are likely to get your message flagged as spam.
3. Domain Reputation. In an attempt to keep ahead of the spammers, ESPs track domain reputations. Spammers used to avoid getting flagged as spam by repeatedly switching servers and IP addresses when sending email. Most ESPs can track the domain associated with email now, and can assign spam grades based on domain alone.
   
   Occasionally this can cause a problem for an innocent party when a new domain owner unwittingly buys a spammer's old domain.
4. Previous Spam Complaints. Having your email flagged as spam by your subscribers is a big problem. While a certain number of spam complaints is unavoidable, if the number of complaints grows beyond a certain percentage, you may find yourself placed on a watch list, which is one step from being blacklisted.
   
   That's why it's important to reduce spam complaints as much as possible. Of course, some people just click the "spam" button instead of unsubscribing. It's the lazy way of getting rid of a subscription they no longer want. It's not fair to the sender, but there's not much we can do about it short of being undeniably lovable. 🙂
5. Subscriber Activity. If your emails regularly have incredibly low open rates or are deleted without being opened, that can be a flag to an ESP that you are sending low quality emails that may potentially be unsolicited. While that alone isn't likely to automatically get your mail blocked, when combined with other spam flags it could push your email over the line.
6. Content. The content of your email is one of the most significant factors in getting flagged or making it through the spam filters. Your choice of words, the subject line, and even image use can all create problems. Writing and designing email has to be as much about deliverability as it is about email performance, because without the deliverability it won't perform. I have a list of spam trigger words if you want to check it out.
7. Too Many Invalid Email Addresses. When too many email addresses bounce back as undeliverable it's a sign that the list may be old and outdated or that was not an opt-in list. It's important to keep your lists clean by regularly deleting invalid email addresses and unsubscribes.
   
   Choose your opt-in method wisely. Most ESPs encourage you to use the double opt-in method. Double opt-in is valuable because you'll know (and have proof) that each and every recipient gave you permission to send them emails. Some hosts will shut your site down first and ask questions later if they get spam complaints. Being able to prove the complainer doube-opted in should quickly resolve the issue.
   
   Don't use purchased, rented, traded, or scraped lists. Not only are they against most ESPs terms of service, but they are notorious for providing bad addresses that lead to high bounce rates and blacklisting. These "garbage lists" don't actually help you grow your business, but they sure can hurt it. Sending to a list that hasn't given you permission can impact your ability to market your business, damage your brand, and even have legal ramifications.
8. Manage Expectations. If subscribers think they're signing up for weekly newsletters and you start sending them daily promotions, you could lose them quickly. Be honest about how often you email and the types of emails you send. If you want to send out different content than they expect, consider starting a new list and give them a chance to subscribe.
9. Easily Accessible Unsubscribe Link. Most ESPs and the law (CAN-SPAM Act in the U.S. and similar laws in many other countries) require that an unsubscribe link be present in every campaign that you send. Don't make it hard to find. That tactic may keep your list artificially larger, but it won't be with active and engaged subscribers. It could cost you more money though, and increase the spam complaints.
10. Headers. Some bulk email software is designed with spammers in mind. Using it can result in technical issues such as incorrectly formatted message headers, lack of a valid message ID, no reverse DNS, PTR records setup, or authentication errors. These lead to deliverability issues and often result in being blacklisted.
11. Subject lines written in ALL CAPS. Don't do it. If it looks like spam—and that definitely does—it will usually be treated like spam.
12. Obfuscation. Attempts to hide the identity of the sender, using links that show one URL in the message but resolve to another, and even server redirects can result in deliverability issues. Also, don't use "IP-address only" links as this is a common spammer tactic to hide the true destination of the link.
13. Relevance. The subject line of each message should be relevant to the body's content and not be misleading. Using misleading subject lines in a misguided attempt to improve the open rate is an old spam tactic. It just makes the recipients distrustful of you and even angry with you. Expect spam complaints if you do this.
14. Monitor Your Affiliates. If you have an affiliate program for your product or service you need to be proactive with your affiliates. Provide guidelines as to what is acceptable promotion and what is not. If your brand becomes associated with affiliate marketing spam, it can affect the mail sent by you and your other affiliates. It is your responsibility to "police" your affiliates and remove the ones who spam.