How to Send Millions of Emails and Avoid Spam Filters

Date: 2021-09-17 | Time of reading: 13 minutes (2472 words)

How to Send Millions of Emails Without Spamming

There are 122 billion email spam messages sent worldwide every day. That's 85% of the world's email traffic. The scale is impressive and upsetting at the same time. Nobody likes spam, especially mailing services. Therefore, many systems are making war on spam. However, bona fide companies also fall under their sanctions. How to avoid becoming a spammer by accident and send emails the right way? Let’s find it out.

What is Spam

Spam is unsolicited bulk messages sent via email or other digital channels such as SMS or social networks. Spammers do such mailings without the recipient's consent to a large number of users. In most cases, letters offer goods or services of dubious quality.

The origins of spam

In the 40s of the last century, the word «spam» had no negative connotation. SPAM was the brand of canned food made by the Hormel Foods Corporation. The company produced it to keep soldiers nourished during World War II. After the war, there were a lot of products left. The Hormel Corporation had to sell them before the end of the shelf life. In short, as quickly as possible. So after a couple of weeks, SPAM canned food ads were all over the place. The product was aggressively imposed on people.

When «junk» bulk messages appeared on the Internet, they began to be labelled with the word «spam». In the beginning, this method could be effective, but now spam messages are annoying. People are used to ignoring them in the large flow of information. But the spam market is not losing momentum.

Spam has penetrated almost all digital communication channels. Besides emails, we run into spam:

  • on forums where users leave messages with hidden advertising;
  • in comments and private messages on social networks;
  • on review sites;
  • in messengers and SMS.

Automation has speeded up the sending of spam and increased it significantly. Now a spam bot can replace a person, for example, when spamming on social media platforms. Although it is not too difficult to determine whether you are communicating with a real person or with a machine. Bots are not very smart, you can break their logic with an unexpected answer.

The types of spam

Ad spam is regular marketing emails that are sent to the addresses in the contact list.

Fake messages are letters from ordinary people who are telling their tragic story and asking for money, or promising to give a large amount just like that:

Example of a spam message from a «real person»Example of a spam message from a «real person»

Phishing emails are sent by spammers who try to fool you by impersonating a well-known brand. The From email contains a fake email address. Usually, the user does not even notice it. He understands that he was deceived after following the link. The goal is to obtain personal and confidential data. A link from this letter leads to a fake website where the user is asked to leave his full name, passwords, bank card numbers and other data.

Phishing email mimicking PayPalPhishing email mimicking PayPal

Malware emails are letters with viruses. The user clicks on the link and gets a virus on his device.

Why do users receive spam?

The reason for spam is data that fell into the wrong hands. How spammers get user addresses:

  • Data leak — the address was stolen from the contact list of the compromised account.
  • Parsing email addresses from websites.
  • Using an email generator that iterates over possible options. Some may turn out to be active.
  • Purchased email lists — they are sold by unscrupulous companies or individual employees.

Who is spamming?

Both professionals and random people such as inexperienced marketers can spam. Spammers are divided into:

  • Pros are mailing services that send out a huge amount of emails. Such teams know their business well, and may even have programmers on staff for more advanced solutions.
  • Email address collectors use software to check and sell databases.
  • Inexperienced and accidental spammers are often marketers who do not understand what a newsletter is and do it wrong. A novice spammer does not delve into the details of the mailing, and that's why his letters fall under the sanctions of the services.

In order not to be among the ranks of accidental spammers, it is necessary to prepare for mailing. You need to know the legal, technical and other peculiarities.

How to avoid spam filters

The spam folder is a sentence for your email. Why? The client will not know about you, the consequences can be more serious: domain disconnection, lawsuits and fines.

To find out why emails end up in the junk folder, you need to evaluate many factors:

  • the legality of mailing;
  • domain reputation;
  • technical settings of the mailing list;
  • whether the rules of the mailbox providers are being followed.

Let's take a look at each point.

The legality of mailing

If you send a commercial email, it must comply with the requirements of the CAN-SPAM Act. Otherwise, you will have to pay a big fine.

How not to break the law:

  • Don’t use false or misleading header information: headers, From names, reply-to addresses, or subject lines.
  • Make it clear to recipients that your message is an advertisement.
  • Tell recipients how to opt out: provide an unsubscribe link.
  • Tell recipients where you’re located. Your message must include your valid physical postal address: street address, a post office box, or a private mailbox.

Domain reputation

The reputation of the domain you use to send emails depends on the following factors:

  • whether the IP address is blacklisted or not,
  • the quality of the email database,
  • whether email authentication passed or not,
  • how many unread emails and spam complaints,
  • how high CTR is,
  • the intensity of mailings.

Database quality

«Bad» addresses in the database also affect the mailing list, so you need to observe email hygiene: clean duplicates and inactive emails.

Possible database problems:

The address was not validated. The user left an inactive or incorrect email.

The base was not used immediately.

In this case, the contacts become obsolete. This happens if a company collects an email database for a long time in different ways, but does not send out messages immediately. For example, because it is waiting for a certain number of customers in the contact list.

Errors in the database

The contact list may contain recipients who have unsubscribed but still receive emails. The risk of receiving spam complaints from such people increases. In the worst case, you can get a lawsuit.

Spam traps in the database

Spam traps are email addresses that are controlled by ISP or blacklist operators. Such addresses are used to find spammers. A spam trap can be an email address that used to belong to a real person, but the user hasn’t logged into the account for a long time. Another type of spam trap is a specially created one. If a newsletter arrives at this address without consent, the service may consider it spam. If there are many such addresses in the database, the sender reputation is getting worse.

Spam complaints

People complain even when they initially consent to the newsletter. What could be the reasons for complaints:

  • unsuccessful or offensive subject line;
  • mailing error — the user received the letter again, although he unsubscribed;
  • change of the mailing subject — "I didn't subscribe to this";
  • partner offers in letters.

User behavior

Mailing services count how often users open emails, click on links inside. The fewer clicks, the more likely you are to get into spam in the future.

Newsletter content

The service may block mailing if your HTML document is not valid. It is forbidden to use dangerous elements, such as JavaScript, VBScript, Frames, IFrames ActiveX, Java applets, CSS connected to external websites, Meta Refresh, etc. Also, services do not accept the links that were shortened with special tools.

Intensity and volume of mailing

Services love predictable behavior. A sudden increase in email volume or sending irregular patterns of emails are signs of spam.


An email blacklist is a list of IP addresses or domains that have been flagged as suspicious for sending spam emails. There are private and public blacklists. Private blacklists are created by users when they restrict the receipt of letters from a specific sender. It’s not too dangerous. However, if a domain or IP address is on a public blacklist, letters can be blocked on a large subset of addresses from this blacklist.

The IP address and domain can get into blacklists for:

  • sending newsletters to irrelevant addresses;
  • a large number of spam traps in the email database;
  • sending emails without the recipient’s confirmation.

Therefore, it is important to check if you are on the blacklists. For example, MXtools will tell you where you’ve been blacklisted.

How to maintain your reputation

  • Use Double Opt-In and continue sending only when the user has confirmed their email.
  • Monitor the ratings of the IP address and domain in special services regularly.
  • Clear the database, get rid of inactive contacts and check for errors.
  • Warm up IP addresses — increase mailing volumes gradually.
  • Monitor the quality of your content and test different engagement techniques if your emails stop opening. But know when to stop and don’t try dubious techniques, for example, clickbait.

Technical settings and email message architecture

All mailing services support the same standards for spam protection. There are technical headers on the servers from which the newsletter is sent. This is where data about the message is placed. This data determines the reliability of the mailing source.

What parameters should be in the «correct» letter:

RFC (Request for Comments) is a document that contains technical specifications and standards.

DNS (reverse DNS lookup and PTR records) — all servers you use to send emails must have valid DNS records. No auto-generated reverse DNS lookup and PTR records. If reverse DNS is not specified, the mail service will not pass such a mailing.

IP addresses (WHOIS). Never hide IP address data in WHOIS. It is especially important when the hoster has been hacked and spam is sent from your IP. If there is no data about you, the service cannot inform you about the problem and will simply block all mailings.

Proxy and Relay are protection against spamming on your behalf. The server does not have to be with an open Proxy server or an open Relay. In this case, anonymous and unauthorized users will not get to it.

DKIM (DomainKey Identified Mail) is a digital signature protocol that determines whether the sender is eligible for mailing. The email provider identifies it through a special key.

SPF (Sender Policy Framework) is a record that will show from which domains and IP the email will come. This setting must be in all DNS, otherwise, the mail service will send a letter to spam or warn of a threat.

FBL (FeedBack Lookup) is a standard that displays information about spam complaints. Each sender of emails can use FBL to find out which user has complained about which email.

List-Unsubscribe is setting the address or URL for unsubscribing. The user can unsubscribe and without clicking through an unsubscribe link.

List-unsubscribe option in GmailList-unsubscribe option in Gmail

DMARC policy is a standard that helps domain owners set rules for their mail services. Using them, the postal provider will know what to do with letters that were sent from the owner's domain, but they did not pass email authentication. This will protect against DKIM forgery and the use of services where any fraud can just put any domain. DMARC also helps control technical settings.

Administrative requirements for mailbox providers

If you want the message to avoid spam filters, the requirements of the mailbox providers must be respected. Otherwise, you may fall under such sanctions as:

  • limitation on email volume;
  • blocking of sending;
  • marked as spam.

Let's take a closer look at the requirements for Gmail.

  1. Configure reverse DNS lookup for IP addresses.
  2. Separate Form addresses by content type. Use the first one to send promotions, the second one to send receipts and the third one for notifications.
  3. Don't send phishing emails from your domain.
  4. Don’t send letters on behalf of another domain if you do not have the right to do so.
  5. Authenticate messages.
  6. Send mail only to interested users who have consented to the newsletter. The service also offers to periodically renew the subscription consent.
  7. Make it easy to unsubscribe.
  8. Send emails on a specific schedule and start sending small batches. The more letters there are, the slower you need to increase their number.
  9. Monitor the reputation of IP addresses: whether they are in blacklists.

Important! Always check the requirements of the mailbox providers before sending emails. Even a small violation of the rules can result in a spam folder.

Altcraft Platform for correct mailings

Our platform helps automate marketing processes and develop business. Marketers use it to send emails without additional services. Altcraft Platform allows:

  • optimize delivery to the inbox folder;
  • bypass blocking;
  • speed up delivery for some categories of letters;
  • reduce sending costs.

The technologies we work with:

SPF (Sender Policy Framework) is a domain authentication technology.

DKIM (DomainKeys Identified Mail) is a digital signature that is automatically verified by the recipient's mail server and clarifies its reputation.

DMARC will tell the mail service what to do if something is wrong with SPF records.

BIMI (Brand Indicators for Message Identification) works with DKIM, SPF and DMARC. Helps to identify companies by the image of the brand next to the subject of the letter. This is additional validation of the sender.

FBL (FeedBack Loop) is a standard that shows spam complaints to the sender of mailings.

With Altcraft Platform, there is no need to worry about emails going to spam. Just create your own newsletter or use a ready-made email template.

Email templates in Altcraft PlatformEmail templates in Altcraft Platform


The path of email newsletters is a thorny and challenging one. One day emails from any company can end up in the spam folder. But don’t give up this channel only because of the complexity. A competent approach and good service will help to send emails correctly and increase sales.







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Author: Lyudmila Kovalenko






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