Why do emails end up in spam?

When a business sends an email campaign or a transactional message, inbox delivery is never guaranteed. Even legitimate emails can end up in spam folders depending on how mailbox providers evaluate the sender and the message.

Spam filtering is based on multiple signals. Providers such as Gmail, Outlook, and Yahoo use automated systems that assess the sender’s technical setup, reputation, message content, and recipient behavior. If the overall trust level is too low, the email may be filtered to spam or blocked entirely.

For businesses sending marketing campaigns or transactional emails at scale, understanding these factors helps improve inbox placement and reduce delivery issues.

How spam filtering works

When an email reaches a mailbox provider, it is evaluated against several criteria, including sender identity, domain reputation, and recipient engagement.

Most mailbox providers check signals such as:

• Domain authentication

• Sending IP reputation

• Historical engagement rates

• Spam complaint levels

• Message structure and formatting

• Sending patterns and consistency

These signals are combined into a trust assessment. If the risk level is considered too high, the message is filtered accordingly.

Spam filtering is dynamic. Reputation and inbox placement can change over time based on ongoing sending behavior.

The most common reasons emails go to spam

1. Missing or incorrect authentication
   Authentication confirms that your domain is authorized to send emails. Key mechanisms include SPF, DKIM, and DMARC. If authentication is missing, misaligned, or incorrectly configured, mailbox providers may treat your email as suspicious. Even correctly built campaigns can be filtered if technical setup is incomplete.

2. Poor sender reputation

   Mailbox providers build a sender reputation profile over time. Reputation is influenced by bounce rates, spam complaints, engagement levels, sending frequency, and volume consistency. A drop in reputation can quickly affect inbox placement across providers.

3. Low quality mailing lists
   List quality directly affects deliverability. Purchased lists, outdated contacts, or low engagement segments can lead to higher bounce rates and low interaction, which mailbox providers interpret as low relevance. This is a common issue when organizations send campaigns to contacts that have not engaged for a long time.

4. Spam complaints
   If recipients mark emails as spam, mailbox providers register that feedback immediately. Even a small percentage of complaints can impact reputation significantly. Spam complaints often increase when recipients do not recognize the sender, receive messages too frequently, or find the content irrelevant.

5. Content and formatting signals
   Spam filters analyze subject lines, message structure, link patterns, and formatting. Certain styles of content can increase filtering risk, especially when combined with poor sender reputation. Examples include emails with misleading subject lines, too many links, or image heavy layouts without enough text context.

6. Sudden volume spikes
   A sudden increase in sending volume can trigger filtering. This often happens when a new domain starts sending high volumes immediately or when an inactive sender resumes with a large campaign. Mailbox providers prefer stable sending patterns, especially when the domain has limited sending history.

Spam causes and how to address them

Spam filtering is rarely caused by a single issue. In most cases, inbox placement is affected by a combination of technical configuration, sending behavior, and recipient engagement. The table below outlines the most common causes of spam placement and the typical actions businesses can take to address them.

Why transactional emails also go to spam

Transactional emails are triggered by user actions such as purchases, password resets, account verification, or service notifications. Because they are expected by the recipient, many businesses assume they are automatically protected from spam filtering. This is not the case!

Transactional emails are evaluated using the same technical and reputation signals as marketing campaigns. If authentication is misconfigured, domain reputation is low, or sending behavior is inconsistent, even critical system emails can be filtered to spam.

Common risk factors for transactional emails include:

1. Shared infrastructure with poor reputation

2. Misaligned sending domains

3. Links pointing to different or unverified domains

4. Sudden spikes in API driven sending

For businesses relying on automated communication, this can directly impact customer experience and operational workflows.

Deliverability and MyLINK MarketingPlatform

MyLINK MarketingPlatform supports structured campaign management, list segmentation, and consent handling. These functions help businesses maintain more controlled sending patterns and better audience targeting.

By working with segmentation and engagement data, organizations can reduce unnecessary sending to inactive contacts and focus on recipients who have opted in and interact with communication.

However, the platform itself does not determine inbox placement. Mailbox providers evaluate the sending domain, authentication setup, historical behavior, and recipient engagement. Businesses must maintain proper configuration and responsible sending practices over time.

Deliverability and MyLINK Email API

MyLINK Email API enables businesses to integrate email directly into applications, websites, and backend systems.

It is typically used for:

• Order confirmations

• Account notifications

• Password resets

• Automated lifecycle emails

• Service updates

When using the MyLINK Email API, businesses remain responsible for:

• Proper SPF, DKIM, and DMARC configuration

• Correct domain alignment

• Gradual scaling of sending volume

• Monitoring bounce and complaint rates

• Maintaining list hygiene where applicable

The API provides reliable infrastructure for sending email at scale. Inbox placement, however, is determined by sender reputation and compliance with mailbox provider standards.

Organizations integrating the API should ensure that technical teams monitor authentication, sending patterns, and domain reputation continuously.

How businesses can reduce spam placement

Reducing spam placement requires both technical setup and operational discipline.

Practical steps include:

1. Configure SPF, DKIM, and DMARC correctly

2. Use consistent sending domains

3. Avoid purchased or outdated contact lists

4. Remove inactive subscribers regularly

5. Segment audiences based on engagement

6. Keep subject lines accurate and transparent

7. Include clear unsubscribe options

8. Monitor bounce, complaint, and engagement rates

9. Scale sending volumes gradually

Improvement typically happens over time. Deliverability is influenced by consistent behavior rather than short term adjustments.

Inbox placement is an ongoing process

Inbox placement is not controlled by one campaign, one setting, or one platform. It reflects long term sender behavior, technical alignment, and recipient interaction.

Platforms such as MyLINK MarketingPlatform and MyLINK Email API provide structured infrastructure for campaign and transactional communication.