Email deliverability: why your emails go to spam

Your invoice did not arrive. A customer says they never got your quote. You look in your sent folder and the email is there, so it went out. Where did it go?

Often, it went to the spam folder, or a receiver quietly dropped it. The cause is usually one of three things: authentication, reputation, or a blocklist. Each one has a clear check, and most of them can be fixed without expensive help.

Why do my emails go to spam?

Mailbox providers such as Gmail and Outlook cannot take your word for it. They need evidence that the message is really from you, and they look at how your domain and server have behaved in the past. When the evidence is weak, or the history is bad, the message is filtered.

The result is the same for your customer: they never see the quote, the reminder, or the invoice. Fixing it is worth the time, because the mail you send is part of how customers decide to trust you.

How do I check whether my email is failing authentication?

Send a test email to a personal account you own, such as a personal Gmail address. Then open the message and find the original headers.

In Gmail, open the message and look for "Show original" in the menu next to it. Look for three results: SPF, DKIM and DMARC. Each should say pass. If one says fail, or nothing at all, that is your first problem to fix.

Ward's free check reads your public records from outside and tells you which of these is missing or broken, so you can compare its answer with your test email.

What does authentication check, and how do I fix it?

Authentication is the set of records that proves mail really comes from your domain. Google's sender guidelines say every sender needs SPF or DKIM, and bulk senders also need DMARC. These are the three records, in plain words:

• SPF lists the servers allowed to send for your domain. A missing SPF record, or one with too many lookups, makes your mail look unauthorized. Add your mail provider and any service that sends for you. SPF is defined in RFC 7208.
• DKIM signs each message with a key published in your DNS. If DKIM is not turned on for a service, its mail cannot be verified. DKIM is defined in RFC 6376.
• DMARC tells receivers what to do when SPF and DKIM fail for your From address. Without a DMARC record, receivers have no clear policy to apply to your domain. The step-by-step setup is in DMARC setup: a step-by-step guide for small businesses.

To fix a missing check, add the record at your DNS host, which is the company that manages your domain's DNS. Then send the test email again and confirm that the result changes to pass.

How does sender reputation affect delivery?

Reputation is the history that receivers keep about your domain and your sending server. It is built from what happens to your mail. Recipients who click "Report spam" lower it. So do bounces, which are messages that come back because the address does not exist, and sending large batches to old lists nobody has opened in a long time.

Good habits help. Send mail to people who asked for it. Remove addresses that bounce. Keep your sending steady instead of sudden large batches. A new domain has no history at all, so start with a small volume to people who expect your mail.

Bulk mail, such as a monthly newsletter, has its own reputation. Microsoft's guide suggests using a subdomain for bulk email services, so that problems with that mail do not affect the reputation of the mail your team sends from your main domain.

What is a blocklist, and how do I know if I am on one?

A blocklist is a public list of servers and domains that mail services use to refuse or filter messages. Being on one usually means spam or abuse was seen coming from your address, or that your domain was used in phishing.

Ward checks your domain and the address of your mail server against several public blocklists, and it tells you which lists, if any, have you listed. Each blocklist is used by some mail services and not by others, so the effect on your mail varies. A listing still matters, because it can block your email at the services that use that list.

Check your results after any change, and also after you clean up a problem. A listing can linger even after the cause is fixed.

How do I get off a blocklist?

Work through four steps, in order. If you skip the cause, the listing can come back.

1. Find which list, and why. Use the list's own lookup page, or Ward's report, to see which list has you and which address it is about. A domain listing and a server listing have different causes.
2. Fix the cause. Common causes are an infected computer, a compromised mailbox, an abused contact form, or a forgotten server that sends mail. Change the passwords involved, clean up what is infected, and close the form or server that is being abused.
3. Ask for removal. Most blocklists have a removal or lookup page on their website. Explain what you fixed, so the list's team can see that the cause is gone.
4. Check again. Removal can take time after you request it. Check the list again later, and confirm that new mail is arriving.

Here is what a finding looks like in Ward for a domain on a list.

If the address belongs to your hosting or mail provider rather than to you, ask the provider to handle it or to move you to another address. You cannot always fix a shared address yourself.

Why do emails land in spam even when I am not listed?

Content and habits matter too. Mail with many links to unfamiliar domains, a message that is mostly one image, or a subject line that promises something it does not deliver can all look suspicious.

Engagement matters as well. If people never open your mail, receivers learn to treat it as unwanted. Keep your list current, and send content your readers expect from you.

What should I check first this week?

• Send a test email to a personal Gmail account and to an Outlook account. Read the authentication results in each.
• Confirm that SPF, DKIM and DMARC pass for every service that sends as your domain.
• Check your domain and your mail server against the blocklists.
• Remove addresses that keep bouncing from your lists.
• If you send a newsletter, move it to a subdomain, so its reputation stays separate from your main mail.

How do I keep my emails out of spam over time?

Look at your authentication setup every few months. A new tool can add mail that fails without any warning, and the DMARC reports are the best early signal. Watch for bounces and complaints, and keep your lists clean.

If a problem comes back, start again with the test email and the authentication results. Then work through the four blocklist steps in order, if a listing is the cause.

For the record checks that come first, read Email spoofing: how to stop someone sending email as you. It covers the same records from the angle of fake mail sent in your name.