Noticed a sudden drop in open rates? Don’t panic! Your subscribers still love you. They probably just never saw your newsletter in their inboxes. Why?
Plummeting open rates are almost always the result of newsletters accidentally ending up in that nasty place we call the junk folder.
We know your newsletter is not junk. Unfortunately, it can still be flagged and there’s not always an obvious reason why your email didn’t pass the test. But you can be proactive and learn how to avoid spam filters with a few best practices!
What is an email spam filter and how does it work?
Believe it or not, spam filters are your friend. Unsolicited emails, commonly known as spam, are a huge problem. There are over 200 billion emails sent daily and 59% of those are spam!
An email spam filter is a program that uses an algorithm to determine if an email is spam. Some of these protocols focus on different aspects of the email such as:
Email header
Header filters are used to identify falsified headers, which are firm proof that an email is spam. Spammers don’t want to be tracked, so they include bogus information in the relay chain to prevent recipients from responding or tracking their location.
Content filters
Filters analyze email content looking for words or phrases that may suggest spam. They utilize mathematical algorithms to analyze a message's content and compare it to records of the user's genuine emails and spam messages.
User-defined filters
User-defined spam filters use the feedback of users to build a database that can be used to identify spam newsletters. Every time a new email is reported as spam, its identifiers are recorded in the central database.
Blocklisted addresses
Blocklist email spam filters prohibit emails from senders who have been added to a spammer's list. Because spammers can readily modify their email addresses, blocklist filters are updated regularly.
User permissions
Some recipients set filters that only allow pre-approved senders to contact them. This is to avoid receiving unsolicited spam newsletters. By contacting these email addresses without approval, you can damage your sender reputation and land in spam.
So, how do you prevent emails from going to spam?
15 ways to avoid spam filters when sending emails
1. Send newsletters from your own domain

It’s perfectly fine to send emails to your friend or colleague from domains like @gmail.com, @yahoo.com, @hotmail.com, etc. However, when it comes to bulk email delivery, it is not a good idea.
To prevent emails from going to spam, you should always send newsletters from your own domain email that matches your website domain name.
Why? Because MailerLite works closely with email clients, such as Gmail and Yahoo Mail, to whitelist your domain or IP address. If you send bulk emails from other domains, you are running the risk of sending your newsletters straight to the junk pile or landing on a blocklist. Spammers will send phishing emails from domains that aren’t their own. So if email client algorithms can’t determine your identity, they may assume you’re sending spam emails.
You should also avoid making frequent changes to your “From” field names, and don’t use strange names like “8wqq823o@yourdomain.com”. Use clear and reliable names like “newsletter@”, “contact@” or “feedback@”.
The best approach is to personalize your address using a real name, e.g. tom@yourdomain.com. It’s much more engaging than something uninviting like “noreply@yourdomain.com”.
Personalization is important in email marketing, in the guide below we'll explain why.
How to create personalized emails that strengthen your bond with subscribers
2. Authenticate your domain

Domain authentication is a method to legitimize your bulk sending domain with our servers so they can send emails on your behalf. You can authenticate your domain by adding new DKIM and SPF records to your DNS panel. This helps email spam filters tolerate your bulk mailing and validates your domain. Domain authentication is a sure-fire way to prove to email accounts that you’re sending legitimate emails.
We wrote a short guide on how to authenticate your email with MailerLite.
3. Maintain a strong sender reputation
Sender reputation is a score given to a sending domain based on the quality of email campaigns, their frequency, size, and subscriber engagement.
To put it simply, your sender reputation is like your Uber rating. If you’re polite and follow all the rules, you get 5 stars. If you’re rude or make a mess, your rating goes down.
3 key events that negatively impact your sender reputation include:
Spam complaints: When users report or mark your email as spam
Email bounces (hard and soft): When recipients on your email list don’t exist, don’t provide permission to receive emails from your domain, and more
Spam traps: Email addresses used for the sole purpose of catching spammers. Any messages sent to these addresses are considered unsolicited
Tip: The best way to maintain a high email sender reputation is to follow the practices outlined in this article.
4. Consider your IP reputation
An IP address is a string of numbers that identifies your computer network’s identity and location. IP reputation is a metric that determines how trustworthy a network is for information and communication.
When using an Email Service Provider (ESP) like MailerLite, users are either using a shared IP, or a
dedicated IP. The benefit of using a dedicated IP address is that there’s no user activity (besides your own) that affects the IP reputation.
Dedicated
IPs require “warming up”which involves sending a low volume of emails on your dedicated IP and then systematically increasing your email volume over a period of time. If the sending volume decreases below 50,000 emails per week, the IP reputation will begin to suffer.
The benefit of shared IP addresses (using default ESP servers) is that the onus isn’t on you to maintain the heavy sending volume required to keep a good reputation. You can send a single email per month and still maintain a good IP reputation.
When choosing an ESP, it’s important to take into account how they manage and maintain the reputation of their servers. For example, at MailerLite we review all accounts before they’re cleared for sending and continuously monitor activity on our servers to ensure that they’re optimized for deliverability. This is, in part, why we rank first in email deliverability among our competitors.
Tip: Email tool tester is an excellent resource when choosing an email marketing platform. They periodically test and review the deliverability of a number of ESPs.
5. Optimize your newsletter copy
Spam filters don’t have the human ability to analyze email copy in context, so they basically flag any email characteristics associated with spam.
How to optimize your email copy to avoid spam filters:
Keep it short. Email spam filters don’t like newsletters that are a mile long. There is not a perfect newsletter length. But if you have more than 200 words or the reader has to work hard to get through it, shorten it
Don’t use too many exclamation points!!!!!!!!!!!!!
Avoid writing text in red
Make sure you are not writing in ALL CAPS. IT FEELS LIKE YOU’RE SCREAMING!
Use spellcheck to ensure your email is written correctly
6. Avoid spam trigger words
While there are no magic keywords to improve your email deliverability, you can limit the use of risky words to reduce the chance of emails going to spam.
The main thing you want to avoid when writing emails is sounding:
Desperate
Pushy
Outlandish (too-good-to-be-true)
Desperate | Pushy | Outlandish |
---|---|---|
Please click here | Action required | 100% free |
Don’t miss this! | Act now | 0% risk |
This is not spam! | No catch | Win $$ |
Promise you | No strings attached | Save big |
Please read | Can’t live without | Cash bonus |
7. Optimize your image-to-text ratio
When spam filters were first built to detect spam phrases, spammers got around this by creating image-only emails. As a result, if your newsletter template has more images than text it’s more likely to land straight in the spam folder.
Additionally, many email clients don’t display images by default (For example Outlook and Gmail) unless the recipient sets images to display by default, or adds the sender to their address book.
Spam filters can vary from client to client, but to ensure maximum deliverability keep your image-to-text ratio around 70-30 in favor of text.
8. Check your link quality
Every domain you link to in an email has a reputation. If you link to a domain with a bad reputation, it will impact your sender reputation. This is because sender reputation is largely determined by domain reputation. So when you link to dubious external sites, your sender reputation is influenced by association.
To protect your link quality:
Link only to legitimate sites with reputable domains
Don’t use link shorteners like bit.ly and TinyURL
Check your affiliate links to ensure that they’re above board
Enable double opt-in on your signup forms—turn bots away at the door by enabling double opt-in on your sign up forms
List of link quality checkers:
9. Test your emails before sending
The best way to understand your customer’s email experience is by sending yourself the exact same email beforehand. Even if you created your newsletter using a template, it’s always a good idea to send a test email.
Sending yourself test emails allows you to review the campaign’s layout and readability. It also allows you to see if your campaign lands in the promotions folder or spam.
To find out why your email is going to spam instead of inbox, you can use a newsletter checker like Inbox insights from MailerCheck to find out exactly what is increasing your spam score.
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Instead of manually checking for hundreds of spam words and other factors, Inbox insights does the job for you. Inbox insights provide an inside look into your newsletter metrics before you send it. That way, if needed, you can tweak exactly what needs to be adjusted rather than overhauling your entire email marketing campaign.
10. Never use purchased lists!
Purchased lists are like ticking time bombs. Sooner or later they will destroy your reputation. Filled with non-existing email addresses and spam traps, they quickly inform mailbox providers that you like to break the rules by sending unsolicited emails.
Your messages will end up in junk folders. Even worse, you may be marked as a spammer.
To send an email using MailerLite, the email recipient must be someone who has specifically asked to receive your emails by opting in or signing up in some way. If you are an online business, it can also be someone who has bought a product or service from you in the past 18 months.
11. Let people unsubscribe
When people unsubscribe from your newsletter it's always a little disappointing. However, you must let people unsubscribe by offering a clear unsubscribe link in every newsletter.
If you don't, you risk the chance that people will mark your email as spam because they don't see any other way to unsubscribe from your emails. So be a good human and make sure the unsubscribe link is part of your newsletter layout. It'll be worth it.
Turn unsubscribes into something positive
Sure you'll end up with one subscriber less on your list, but you can give a positive twist to unsubscribes. When you add a survey to your unsubscribe page, you can collect feedback and take notes on why people are no longer interested in your emails. With each unsubscribe, you now at least get the opportunity to improve your email marketing.
12. Put some thought into your subject line
Your email subject line is crucial for your open rate, but it's also an important part of reducing spam marks. People can take a quick look at your subject line and decide to mark it as spam. That's why we advise you to put some thought into your subject line. You can use the tips mentioned earlier (avoid all caps, fishy phrases, and excessive use of exclamation marks) to create a risk-free subject line.
In most cases, you'll be more than fine if your subject line is relevant and written with the reader in mind.
Learn how to write a winning subject line in this guide:
How to write the best email subject lines to boost open rates
13. Clean your email list regularly
The most effective way to optimize your email deliverability is to keep a healthy email list made up of valid and engaged subscribers.
To maintain a high-quality email list, start by using these 4 strategies:
Send ultra-relevant emails using groups (aka email tagging) - By only sending subscribers newsletters they want to read, your overall engagement will increase
Re-engage inactive subscribers with win-back email campaigns - Give your subscribers one last chance to engage with your content. If they’re still not interested, delete them off your list and make room for more engaged subscribers
Enable double opt-in on your signup forms - Turn bots away at the door by enabling double opt-in on your sign-up forms
Regularly clean your list using a mail tester (we love MailerCheck). Doing this will make sure all invalid email addresses, like hard bounces, are filtered out of your list. This is particularly useful for email marketers migrating their address book from another ESP (email service provider) to MailerLite.

A clean list will avoid spam trap hits and reduce the risk of your sender reputation getting damaged.
Want to learn more about list hygiene? In our article on how to improve your own email deliverability, we'll explain how you can identify and remove email addresses that aren't doing your subscriber list any good.
8 best practices to improve email deliverability
14. Comply with anti-spam laws
The CAN-SPAM Act is a law that sets the rules for commercial email. Besides avoiding hefty fines, complying with the rules laid out in the CAN-SPAM Act greatly can greatly improve your email deliverability.
Some of the main requirements outlined in the CAN-SPAM Act include:
Tell email recipients where you’re located - Your message must include your valid physical postal address. This can be your current street address, a post office box, or a private mailbox. You can automatically include your company name and address in your email footer in your account settings
Tell recipients how to opt-out - Your message must include a clear and conspicuous explanation of how the recipient can opt-out of getting an email from you in the future. Luckily MailerLite will remind you if you forget to include an unsubscribe link in your newsletter
Honor opt-out requests promptly - You must honor a recipient’s opt-out request within 10 business days. Luckily, MailerLite handles this for you by automatically removing subscribers who unsubscribe from your active list. But keep in mind that some subscribers may reply to your newsletter and ask to be removed, you will need to remove these subscribers from your list manually
15. Ask subscribers to whitelist you
Whitelisting is when an email recipient adds a sender’s address to a list of approved senders so that emails from that address are never filtered as spam. Instead, when a recipient adds an email address to their whitelist, they are verifying that they trust the sender. This instructs the subscriber’s email client to send messages straight to the inbox.
When you ask subscribers to whitelist you, send them a quick set of instructions to make it super easy.
Avoiding the spam folder for good
Remember, you are only as good as your reputation. No matter how honest and good-willed your message is, your subscribers will never see it if you get a bad rep. Follow the simple tips above and you will avoid most email spam filters, stop your emails from going to spam, and keep your sender reputation healthy.
Editor’s note: This post was originally published in January 2015, but has been revamped and updated for accuracy and comprehensiveness.
FAQs
What precautions can be taken to avoid spam emails? ›
- Never give out or post your email address publicly. ...
- Think before you click. ...
- Do not reply to spam messages. ...
- Download spam filtering tools and anti-virus software. ...
- Avoid using your personal or business email address.
Poor deliverability rates
As you can see from the above image, Mailerlite has delivered 16.33% of emails to spam folders and 4.61% of emails to nowhere (probably got lost).
- Never buy email lists. ...
- Follow list hygiene practices. ...
- Avoid sending emails with attachments. ...
- Maintain the text to image ratio. ...
- Ask your subscribers to whitelist your email address. ...
- Include the View Online link in your emails.
- Correctly format headers. ...
- Ensure the email underwent a checkout. ...
- Use a special header. ...
- Include an Unsubscribe Link. ...
- Avoid using spam-like words. ...
- Don't use suspicious links and attachments. ...
- Check the design. ...
- Provide a plain-text version.
Sensitive information such as passwords, bank account numbers and social security numbers should never be sent via email. CenturyLink, PayPal and your bank are examples of companies that would never ask for personal information in an email.
What does a spam filter do? ›A spam filter is a program used to detect unsolicited, unwanted and virus-infected emails and prevent those messages from getting to a user's inbox.
How do I stop emails I send going to junk? ›Open your Junk Email folder and select the messages you want to keep. From the top toolbar, select Not junk > Not junk (or Not spam > Not spam). You can also open the message and select the It's not junk link at the top. next to their name.
Why are my newsletters going to spam? ›The first and most obvious reason for your emails ending up in spam is because your recipients put them there. Even if your content is strong and the recipient expressly gave you permission to contact them, they may still decide to mark your email as spam as a way to clean up a cluttered inbox.
What triggers a spam filter? ›Emails that use too many images, or are all one image, could trigger a spam filter. Using several lines of text to offset the images can help prevent this. Additionally, some filters are sophisticated enough to detect an image's content, so it's best to avoid any photos with explicit content.
How many emails can you send without being flagged as spam? ›You may see this message if you send an email to a total of more than 500 recipients in a single email and or more than 500 emails sent in a day. When you get this error, you should be able to send emails again within 1 to 24 hours.
How many emails can I send before I get blacklisted? ›
If you send 10,000 emails at once and there's a high bounce rate, you'll get blacklisted when the rate goes above 10%. Sending fewer emails as you warm up the IPs will help prevent that situation. Remember, more is not always better when it comes to sales leads.
Which is a filter that removes spam mails? ›1) SpamTitan (TitanHQ)
SpamTitan is suitable for all types of businesses. It scans your emails, including links and attachments, and blocks any threats it finds. Founded in 1995, TitanHQ offers an affordable spam filter from just $0.80 per user per month.
- On your Android phone or tablet, open the Gmail app . Note: If you don't have the Gmail app, download it.
- In the top left, tap Menu. Spam.
- Open the email.
- In the top right, tap More. Report not spam.
- Don't Open Unexpected Attachments. Viruses are often sent via email attachments. ...
- Use Spam Filters. UCI has many safeguards in place to rid you of unsolicited email or spam. ...
- Beware of Spoof Emails or Phishing. ...
- Don't Send Sensitive Data in Email. ...
- Avoid clicking on links in the body of an email message.
- Don't write like the reader is your best friend. ...
- Don't assume the reader knows who you are and why you are emailing. ...
- Don't use informal language and emoticons. ...
- Don't ramble on and on and on. ...
- Don't forget to proof read for spelling and grammar mistakes.
- Use a strong email password. ...
- Use two-factor authentication. ...
- Monitor your email habits. ...
- Look out for “Phishing Emails” ...
- Don't open attachments without scanning them first. ...
- Never access emails from public WiFi. ...
- Change your password as often as possible. ...
- Be careful with the devices you use.
SPAM is an acronym: Special Processed American Meat.
What is an email filtering solution? ›An email filtering service is a process of filtering emails that are inbound to the user's mailbox and outgoing from the user's server. Inbound email filtering checks and filters the incoming emails for spam, malware, suspicious links, etc. and also organizes the messages into different categories or folders.
Why do I keep getting spam emails in my inbox? ›Spam messages often come from illegitimate email addresses, and may contain explicit or illegal content. These emails often use scare tactics, contain typos and misleading information, and are sent in bulk from an anonymous sender.
Why is my junk mail going to my inbox? ›A lot of unwanted messages make their way into your inbox when you order a product or subscribe to a mailing list—and then the company automatically signs you up to receive unwanted marketing updates or shares your contact information with an advertiser.
What is Junk Email in your inbox? ›
Email spam, also known as junk email, refers to unsolicited email messages, usually sent in bulk to a large list of recipients.
Can I have 2 Gmail accounts? ›Can I Have Multiple Gmail Accounts? The short answer is, "Yes, you can have multiple Gmail accounts." Many professionals have both a personal Gmail account and a work Gmail account tethered to their CRM.
What is the safest email account to have? ›- ProtonMail. ProtonMail is the most well-known secure email provider. ...
- Mailbox.org. Mailbox.org is a secure email service aimed at business users looking for an alternative to Google or Microsoft tools. ...
- HubSpot. ...
- Zoho Mail. ...
- Tutanota. ...
- Posteo. ...
- Thexyz. ...
- PrivateMail.
- Manipulative: creating unnecessary urgency or pressure.
- Needy: sounding desperate or exaggerated claims.
- Sleazy: being too pushy.
- Cheap: no pre-qualifications, everybody wins.
- Far-fetched: statements that are too good to be true.
- Shady: ethically or legally questionable behavior.
Implementing spam filtering is extremely important for any organization. Not only does spam filtering help keep garbage out of email inboxes, it helps with the quality of life of business emails because they run smoothly and are only used for their desired purpose.
How many emails is too many? ›More than 50 emails overwhelms employees, survey says.
How many emails can I send per day? ›1. What is the daily limit for sending emails in Gmail? Gmail claims that with a regular Gmail account you can send 500 emails/day. And with paid services like G Suite(Google Workspace), you can send over 2,000 emails/day.
Is there a limit to how many emails you can send? ›...
Gmail sending limits.
Limit type | Limit |
---|---|
Total recipients per day Email addresses (recipients) count each time a message is sent; 5 emails sent to 10 addresses count as 50 total recipients.* | 10,000 1,500 for multi-send |
- If you're managing your email delivery, then check your return path/abuse mailbox, if your domain is on the blacklist. ...
- If you're using some Email Service Provider (ESP) like Pepipost, then contact them to help your domain to get removed from the blacklist.
A website may be IP blacklisted if its content is deemed inappropriate. This could be pornographic material, black market trade, or sensitive subjects such as weapons and arms deals. Internet Service Providers or even government agencies could actively block websites such as these and prevent users from accessing them.
How many email accounts can I have with one phone number? ›
Gmail accounts per phone number
You can have up to four Gmail accounts verified with the same phone number.
...
Block an email address
- On your computer, go to Gmail.
- Open the message.
- In the top right, click More .
- Click Block [sender].
- To block someone in Outlook.com, select the messages or senders you want to block.
- From the top toolbar, select Junk > Block (or Spam > Block).
- Select OK. The messages you select will be deleted and all future messages will be blocked from your mailbox.
Look closely at the sender's address.
Spammers will often impersonate reputable institutions in an attempt to gain access to your data. In doing so, they will sometimes create a fake email address that resembles the real one. For example, a PayPal spam email may be sent from an address ending in “@paypai.com”.
You should check that the target mailbox or mail folder isn't full or disabled. If the level of spam you receive continues to increase, then you should consider being wary of where your email address is given. Many spammers will trawl websites for email addresses in plain-text, to add to their mailing lists.
What triggers a spam filter? ›Emails that use too many images, or are all one image, could trigger a spam filter. Using several lines of text to offset the images can help prevent this. Additionally, some filters are sophisticated enough to detect an image's content, so it's best to avoid any photos with explicit content.
Are there any free spam filters? ›Over 8 million people use MailWasher as their spam filter! MailWasher is free to use and won't ever expire. It works with Outlook, Outlook Express, Incredimail, Thunderbird, Windows Live Mail, GMail, Hotmail, Yahoo, EM Client and every other email program.
What is an email filtering solution? ›An email filtering service is a process of filtering emails that are inbound to the user's mailbox and outgoing from the user's server. Inbound email filtering checks and filters the incoming emails for spam, malware, suspicious links, etc. and also organizes the messages into different categories or folders.
How do you stop a spam bomb? ›6 steps to take during an email bombing
Avoid mass deletion and use email rules to filter spam instead. Inboxes that are critical to your organization should use failover services and notifications to protect against the deletion of important emails.
You may have unsubscribed previously to a spam email in error, or you may have replied in error, or in some cases a person may be signing you up for malicious reasons. (see above) Either just mark as Spam in the normal way, if they are in your Inbox, or if asking for personal information, report as phishing.
Why am I getting so much spam all of a sudden 2022 Gmail? ›
The usual source of a sudden increase in failed login attempts or spam mail received is that the email address was harvested by a hacker who breached a data base on a website where you subscribed to something. That database gets repeatedly sold to other hackers/spammers on the dark web.
How do I change my spam filter settings in Outlook? ›- Click Home > Delete group > Junk > Junk E-mail Options.
- Choose the level of protection you want.