If your emails keep landing in spam, there may be a problem with authentication, sender reputation, recipient expectations, or the way you send messages. Changing the subject line alone rarely fixes a persistent delivery problem. First find out whether the issue affects one recipient, one email provider, or most of your audience.
Start by narrowing down the problem
- One recipient only: their spam filter, organization policy, or previous interaction with your messages may be involved.
- One provider only: compare results across Gmail, Outlook.com, or other providers, then consult the affected provider's sender guidance.
- Many recipients across providers: check authentication, sending volume, list quality, and account security.
- The problem started suddenly: review recent DNS changes, a new email platform, an unexpected sending spike, and signs of unauthorized access. If you suspect a compromised account, follow this guide to check whether your email account was hacked.
Step 1: Check authentication for your domain
If you send from a custom domain, check SPF, DKIM, and DMARC. These records help receiving providers verify that your messages are authorized and that the visible sender domain aligns with the authenticated domain. They improve trust, but passing them does not guarantee inbox placement.
- SPF: identifies the servers and services authorized to send mail for your domain.
- DKIM: adds a cryptographic signature that the receiving server can verify.
- DMARC: lets the domain owner set a policy for messages that fail authentication and check alignment with the visible From domain.
Get the exact DNS values from every service that sends mail for your domain, such as your mailbox provider and newsletter platform. Do not copy a generic record and assume it fits your setup. A domain should have one SPF record; if multiple services send mail, combine their authorized mechanisms into that record according to the providers' instructions.
A monitoring policy such as p=none can help you observe DMARC results before enforcing a stricter policy, but it does not itself prevent spoofing. Confirm that legitimate senders are accounted for before changing the policy.
Step 2: Check the result on an actual message
- Send a test message to a Gmail account you control, if Gmail is one of the affected destinations.
- Open the message and use the three-dot menu to choose Show original.
- Review the authentication results for SPF, DKIM, and DMARC, where shown. Also check whether the message arrived in the inbox or spam.
If authentication fails, fix that before making lots of changes to message wording. If authentication passes but the message still goes to spam, move on to reputation, recipient engagement, and sending practices. For general Gmail sending or receiving failures, see this Gmail troubleshooting guide.
Step 3: Review who you send to and how often
- Send to people who expect your messages. Purchased or scraped lists can generate complaints and invalid-address hits that damage reputation.
- Remove hard bounces. Stop sending to addresses that are confirmed invalid. If you receive a bounce notice, use this guide to interpret email bounce errors.
- Make subscriptions clear. For newsletters, use a clear opt-in process and keep records of consent. Double opt-in can help reduce typos and unwanted signups.
- Make unsubscribing easy. Bulk and subscription senders should follow the relevant provider requirements for visible unsubscribe links and one-click unsubscribe where required, and process requests promptly.
- Avoid sudden volume spikes. If you are starting with a new domain or service, build volume gradually and monitor delivery results. Do not send a large batch all at once to an old or unengaged list.
- Separate different kinds of mail when practical. Receipts and password-reset messages have different purposes from promotions. Separate streams or subdomains may help isolate reputation issues, but configure authentication correctly for each.
Step 4: Review the message itself
Content is only one part of spam filtering. There is no universal list of “spam words” that reliably predicts delivery. Instead, look for signs that could mislead recipients or make the message difficult to trust:
- A subject line or sender name that misrepresents the message.
- Links that redirect through unfamiliar domains or lead somewhere different from what the text promises.
- Attachments recipients did not expect, especially large or unusual files.
- A newsletter with broken formatting, broken links, or no usable plain-text alternative.
- Promotional messages sent without a clear reason for the recipient to expect them.
Make one meaningful change at a time and compare results with the same recipient provider. Sending repeated tests to random addresses or changing many things at once makes it harder to identify the cause.
Step 5: Check reputation and provider feedback
- For Gmail delivery: Google Postmaster Tools can show available information about spam rates, authentication, and domain or IP reputation. Data may be limited when sending volume is low.
- For Outlook.com: consult Microsoft's sender support guidance if delivery problems persist there.
- Check blocklists carefully. A public blocklist result is a clue, not proof that it caused the problem. Check the specific rejection message and ask your email host whether the sending IP is shared.
- Use inbox-placement tests as diagnostics. Third-party testing tools can help identify configuration issues, but their results do not guarantee that every recipient's provider will place a message in the inbox.
For Gmail, Google advises senders to keep the reported spam rate below 0.10% and avoid reaching 0.30% or higher. These figures come from Google's Postmaster guidance and are not universal thresholds for every provider or every type of sender.
If you are the recipient
If a legitimate message from someone else lands in your spam folder, mark it as Not spam and add the sender to your contacts or safe-senders list if your email service supports it. This may help your own mailbox learn your preference, but it does not repair the sender's domain authentication or reputation for everyone else.
What not to do
- Do not assume that changing a few words or adding more images will fix the problem.
- Do not switch domains simply to escape a poor reputation; the underlying sending practices may cause the new setup to suffer too.
- Do not treat a whitelist request or a single test-tool score as a permanent solution.
- Do not keep sending to invalid addresses or people who did not ask to receive your messages.
Bottom line
First identify which recipients and providers are affected. Then check authentication, review bounce or rejection details, and investigate list quality and sending patterns. If authentication passes and the issue persists with one provider, use that provider's sender guidance or ask your email service for help. Improvements may take time; there is no setting that guarantees inbox placement.