Sending newsletters is one of the most effective tools to maintain direct contact with your audience. Yet many website owners find themselves faced with the frustration of their emails ending up in the spam folder. That's why we thought we'd publish a practical guide on how to send emails without them going to spam.

Spam filters are incredibly useful, but they can hurt the open and conversion rates of legitimate services and promotions, derailing your marketing efforts. But why does this happen? And how can you avoid it?

Below we analyze the main reasons why a newsletter might be marked as spam and the strategies to ensure that your messages actually reach the recipient's primary inbox.

1. Incorrect mail server configuration

One of the most common reasons why emails are filtered as spam has to do with the configuration of the server from which they are sent. 

If your website uses an improperly configured email service, email providers may interpret your messages as potentially dangerous.

SPF, DKIM and DMARC authentication

Email authentication standards are essential tools to prevent your messages from being blocked:

• SPF (Sender Policy Framework): Verify that the server sending the email is authorized by the domain.
• DKIM (DomainKeys Identified Mail): adds a cryptographic signature to ensure the integrity of the message.
• DMARC (Domain-based Message Authentication, Reporting, and Conformance): establishes a policy on how to handle emails that fail SPF and DKIM checks. This is an additional tool but also potentially dangerous if a service sends emails from multiple different servers (for example, if you use a transactional email service, such as Amazon SE): if a server is not authenticated it will not be able to send emails correctly

Without proper configuration of these protocols, email providers may identify your newsletter as suspicious and automatically move it to the spam folder.

2. IP address with bad reputation

The IP address of the server from which you send emails directly affects the likelihood of your messages ending up in spam. 

If you use a shared email service, your IP may have been flagged for spam by other users of the same platform.

How to check IP reputation?

You can check if your IP is in a blacklist using online tools such as:

• MXToolBox
• Spamhaus
• Barracuda Reputation Block List

If your IP has been flagged, you may need to request removal from blacklists or consider using an email provider with a more reliable infrastructure.

3. Email content considered suspicious

Spam filters analyze the content of emails for elements that might indicate spam. Some common errors include:

Sensitive words and phrases

The use of terms such as free of charge, exclusive offer, click here, earn fast can activate spam filters. It is preferable to use natural and contextualized language.

Excess capital letters and symbols

An object like "BUY NOW!!!" may be immediately flagged as spam. Avoid excessive use of capital letters, exclamation points, or special symbols.

Suspicious links

Inserting too many links or using shortened URLs (such as those generated by bit.ly or TinyURL) can make filters suspicious, especially if the destination domain is little-known or has been flagged as dangerous.

Sending frequency and user behavior

Sending too many newsletters in a short period of time can be interpreted by email providers as spam. 

User behavior also has an impact! 

If many people mark your emails as spam, your sender reputation will suffer.

So, how do you manage your sending frequency?

• Avoid sending emails too frequently without a real need.
• Give users the ability to choose how often they receive communications.
• Analyze your open rates and adjust accordingly.

If many people ignore or delete your emails without opening them, providers may consider them irrelevant and start filtering them.

Lack of customization and low quality of contact list

Sending generic, impersonal emails increases the likelihood that users will ignore them or mark them as spam. Additionally, a low-quality contact list (e.g., purchased or out-of-date) can contain many invalid addresses, hurting your domain reputation.

Solutions to improve the quality of your contact list

• Collect email addresses only from genuinely interested users.
• Use a double opt-in system to confirm subscriptions.
• Delete inactive or non-existent addresses regularly.

A well-maintained contact database reduces the risk of your messages being perceived as unwanted.

Lack of a clear unsubscribe option

One of the most important requirements of email marketing is that users can easily unsubscribe. If you don’t include a clearly visible unsubscribe link, users may report your newsletter as spam, damaging your domain’s reputation.

To comply with regulations (such as the GDPR in Europe and the CAN-SPAM Act in the United States), make sure that each email contains an unsubscribe link and that the process is simple and straightforward.

Strategies for send emails without them ending up in spam and improve delivery rate

In summary, here are some concrete actions to reduce the risk of your newsletters ending up in spam:

• Correctly configure SPF, DKIM and DMARC to authenticate your emails.
• Check IP reputation from which you send messages.
• Avoid suspicious words and formatting, like all caps and too many symbols.
• Monitor your sending frequency so as not to overload users.
• Update your contact list regularly to avoid inactive emails.
• Offer a clear unsubscribe option to comply with regulations and reduce spam reports.
• If you think you will need to send a lot of emails or newsletters to a lot of recipients, rely on a transactional email service such as Mailgun, AmazonSES or Sendgrid).

By applying these best practices, you will improve the deliverability of your newsletters, increasing the likelihood that your messages will be read and generate interactions. If you don't know how to do it and you need advice on sending mass emails, contact us.