Why Are My Emails Going to Spam? Causes and Fixes

If your business emails are going to spam, the messages you send are not reaching the people who need them. Quotes go unanswered, invoices are paid late, and follow-ups are never seen, because they were filtered before reaching an inbox.

Emails do not land in spam at random. Providers like Google and Microsoft run a defined set of checks on every incoming message. This guide explains what those checks are, which failures are most common for business senders, and how to fix them.

How Email Providers Decide What Goes to Spam

Every incoming email is scored before it is delivered. The receiving server checks whether the sender can be verified, reviews how previous messages from the same domain were received, and examines the content of the message itself.

The checks fall into three categories:

Authentication — whether the receiving server can verify the email genuinely came from your domain
Sender reputation — the track record of your domain and sending servers, built from complaints, bounces, and engagement on past messages
Content and list quality — whether the message resembles known spam, and whether it was sent to people who agreed to receive it

Missing Authentication Is the Most Common Cause

For most businesses, the most common reason emails go to spam is missing or misconfigured email authentication. Authentication is set up through three DNS records.

SPF (Sender Policy Framework) lists the servers that are allowed to send email for your domain. If a message arrives from a server that is not on the list, receiving servers treat it as suspect. Our guide to SPF explains how it works.

DKIM (DomainKeys Identified Mail) adds a digital signature to each message, which proves the email was not altered in transit. Messages without a valid signature receive less trust from receiving servers. See our guide to DKIM.

DMARC ties SPF and DKIM together and tells providers how to handle messages that fail. Google and Yahoo have required DMARC from bulk senders since February 2024, and a missing record now directly affects deliverability. Our guide to DMARC covers it in detail.

Authentication has to cover every service that sends email on your behalf: your mail provider, newsletter platform, CRM, invoicing software, and booking system. A service that was never added to your records sends unauthenticated email every time it runs, which gradually damages your domain's standing.

How Sender Reputation Works

Email providers keep a history of your domain and the IP addresses you send from. That history determines how much trust new messages receive. With a poor reputation, even authenticated, well-written emails can be filtered.

The main factors that damage reputation:

Spam complaints — recipients marking your messages as junk. Google's enforcement threshold is 0.3% of delivered mail, and delivery problems begin well below that
High bounce rates caused by sending to old or purchased lists containing invalid addresses
Sudden volume changes, such as a large one-off campaign from a domain that normally sends low volumes
Shared sending infrastructure — on some platforms your messages share IP addresses with other customers, and their behaviour affects your delivery

Content Problems That Trigger Filters

Content carries less weight than authentication and reputation, but it can move a borderline message into spam.

Known triggers include subject lines written in all capitals, phrases such as "free" and "act now", link shorteners that hide the destination URL, attachments the recipient was not expecting, and emails consisting of a single large image with little text.

List quality matters as well. Sending to people who did not sign up produces spam complaints, and complaints affect the reputation of everything you send afterwards.

How to Diagnose Why Your Emails Go to Spam

Check authentication first, because it is the most common failure and the quickest to confirm. The free scanner on this page checks your domain's SPF, DKIM, and DMARC records and reports their status in seconds.

Then send a test email to a Gmail address and use the "Show original" option on the received message. It displays whether SPF, DKIM, and DMARC passed for that specific email.

For higher sending volumes, Google Postmaster Tools reports your domain reputation and spam complaint rate as Gmail measures them.

How to Fix It

The fixes follow the same order as the causes. Authentication comes first, because reputation cannot recover while authentication is failing.

Publish a correct SPF record that includes every service sending email for your domain
Enable DKIM signing in each of those services — most provide a setting that generates the DNS record to publish
Publish a DMARC record, then move it to enforcement once reports confirm all your senders pass
Remove addresses that bounce and contacts who never open your messages
Keep sending volume consistent and send only to people who opted in
Recheck authentication whenever you add a new tool that sends email on your behalf

Check your domain now

Enter your domain to see your current email security status.

Frequently Asked Questions

Why are my emails suddenly going to spam?

Sudden changes usually have a specific cause: a new sending tool added without authentication, a DNS change that broke SPF or DKIM, a campaign that generated complaints, or a provider tightening its requirements. Checking your authentication records is the fastest way to identify which one applies.

Can fixing SPF, DKIM, and DMARC get my emails out of spam?

Often, yes — authentication is one of the main signals providers use to decide whether to trust your email. But it is one factor among several: content, sending habits, list quality, and sender reputation all play a part, so fixing authentication alone doesn't guarantee inbox placement. It removes the most common technical reason for filtering.

Why do my emails go to spam in Gmail but not Outlook?

Each provider runs its own filtering and weighs signals differently. Gmail places significant weight on authentication and on how recipients engage with your messages, while Microsoft relies more on its own reputation systems. Passing SPF, DKIM, and DMARC is the common requirement that improves delivery with all of them.

Does marking my own emails as 'not spam' help?

It only trains that one mailbox. Marking a message 'not spam' teaches that recipient's filter to accept your address, but it does not change why the message was filtered. If authentication is failing or your domain's reputation is poor, your emails continue to be filtered for everyone else.

Emails going to spam have identifiable causes: failed authentication, damaged sender reputation, or content and list problems. Each can be diagnosed and corrected, and authentication is the place to start.

Enter your domain above to check your SPF, DKIM, and DMARC records now.

If the scan shows gaps, readyDMARC fixes them for you — we configure the records, manage the rollout, and monitor your domain afterwards. See our managed email security services for details.

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