Why does my email go to spam?

Quick answer

You send an important quotation to a customer.

Or an invoice.

Or simply an email that you expect them to read.

A few hours later you discover that it never reached their inbox. Instead, it ended up in the spam folder.

If this has happened to you, don't panic.

In most cases, your mail server is working correctly. The problem is that services such as Gmail, Microsoft 365 and Yahoo analyse many different signals before deciding whether a message belongs in the inbox or in the spam folder.

The good news is that many of the most common causes can be identified and corrected.

Common symptoms

This problem usually appears in one or more of the following ways:

• Some customers receive your emails while others do not.
• Gmail places your messages in the spam folder.
• Outlook warns recipients that the sender cannot be verified.
• Emails sent from your mobile phone fail more often than emails sent from webmail.
• Quotations or invoices never reach the recipient.
• The problem started after changing your email provider, hosting provider or DNS configuration.

Common causes

There are many reasons why a legitimate email may be treated as spam.

The most common are:

• your domain does not have a valid SPF record;
• DKIM is not enabled or does not match your DNS configuration;
• no DMARC policy has been published, or it is incorrectly configured;
• your mailbox has been compromised or is sending an unusually high number of messages;
• your email application is sending through the wrong SMTP server;
• your domain or mail server has developed a poor sending reputation;
• the content or structure of the message triggers spam filters.

It is important to understand that modern spam filters do not rely on a single factor. They analyse many different signals before deciding whether to trust a message.

Diagnosis

Before making any configuration changes, perform a few simple checks.

1. Send a test message to an external email account.
2. Check whether it arrives in the inbox or the spam folder.
3. Review the message headers and verify that SPF, DKIM and DMARC all pass successfully.
4. Compare sending from your usual email application with sending from webmail.
5. If you are a PRIMARI.NET customer, send the same message from webmail.primari.net. If it works correctly from webmail but not from Outlook or your mobile phone, the problem is usually related to your local email client configuration rather than the mail server itself.
6. Check whether your mailbox has sent messages that you do not recognise.

These simple checks often help determine whether the problem lies with your computer, your mailbox or your domain configuration.

Solutions

The right solution depends on the underlying cause.

Typical corrective actions include:

• correcting your domain's SPF record;
• enabling DKIM;
• publishing a sensible DMARC policy, starting in monitoring mode;
• configuring your email application to use authenticated SMTP correctly;
• changing your mailbox password if unauthorised access is suspected;
• reviewing the content and structure of the message before sending.

Avoid making several configuration changes at the same time. It is much easier to identify the real cause when changes are made one step at a time.

When to contact PRIMARI.NET

If your emails continue to end up in the spam folder after carrying out the basic checks, it is probably time to investigate the problem in more detail.

At PRIMARI.NET we regularly help customers diagnose problems involving:

• SPF;
• DKIM;
• DMARC;
• DNS configuration;
• sender reputation;
• email client configuration;
• mailbox security.

No email provider can guarantee that every message will always reach every recipient, because every receiving organisation applies its own filtering policies.

However, a correct technical configuration significantly reduces avoidable delivery problems.

If you would rather have an experienced engineer review your configuration, we will explain what is happening, identify the most likely cause and recommend the safest way to resolve the problem.