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

Each mailbox has its own rules. Gmail checks SPF, DKIM and DMARC alignment strictly and has extra rules for bulk senders, so an email that Outlook accepts can still fail one of Gmail's checks. A test shows the verdict for each mailbox side by side.

Do Gmail's sender rules apply if I only send a few emails a day?

Yes, the basic rules apply to everyone sending to personal Gmail accounts. Every sender needs SPF or DKIM to pass, valid reverse DNS, an encrypted connection and a low spam complaint rate. The stricter bulk rules start at 5,000 messages a day.

Will adding a DMARC record stop my emails going to spam?

Only if SPF or DKIM already passes for your own domain. A DMARC record tells Gmail what to do when checks fail; it doesn't make them pass. Start with p=none so nothing changes while you check your reports.

Does Gmail treat Google Workspace inboxes the same way?

Google Workspace uses the same spam filtering, but Google says its sender requirements and enforcement apply to personal Gmail accounts. Mail that fails the checks is more likely to land in a Workspace user's Spam folder than to bounce.

Can a test email tell me my spam complaint rate?

No. Your complaint rate comes from how real recipients react over time. Google's free Postmaster Tools shows it once you send enough email to Gmail. A test email checks the technical side, which is the most common cause.

Why does Gmail put my emails in spam?

Gmail puts your emails in spam when it can't confirm they really come from your domain, or when your sending breaks one of its sender rules. The usual causes are a missing or broken SPF or DKIM record, a From address that doesn't match (align with) either of them, no DMARC record, or too many people clicking "Report spam".

The good news: most of these are settings, not reputation. Once you know which rule you fail, the fix is usually one or two DNS records.

What Gmail checks first: authentication

Gmail wants proof that an email claiming to be from yourbusiness.com was really sent by you. It uses three standards:

SPF: a DNS record that lists the servers allowed to send email for your domain.
DKIM: a digital signature that proves the email came from your domain and wasn't changed on the way.
DMARC: a DNS record that tells receivers what to do with email that fails SPF and DKIM, and sends you reports.

Since February 2024, Google has required every sender to personal Gmail accounts to:

pass SPF or DKIM
send from a server with valid forward and reverse DNS (the server's name and address point to each other)
send over an encrypted (TLS) connection
keep the spam complaint rate below 0.3%
format messages correctly and not pretend to be from a Gmail address

Since November 2025, Google has been tightening enforcement. Mail that fails these requirements can now be delayed or rejected outright, not just filtered to spam. That is why some senders now see a bounce such as 550 5.7.26 instead of a missing email.

Alignment: the step most people miss

Many people find that SPF and DKIM both "pass", yet Gmail still sends their email to spam. The reason is usually alignment.

Alignment means SPF or DKIM passed for the same domain that appears in your From address. If you send a newsletter through an email service, it may sign the email with its own domain, not yours. That proves the email wasn't changed, but not that it came from yourbusiness.com. For DMARC, that pass doesn't count.

The fix is to turn on "domain authentication" (sometimes called a custom sending domain) in each service that sends email as you. The service then gives you DNS records so it can sign with your domain.

The bulk-sender rules

If you send 5,000 or more messages a day to personal Gmail accounts, Google treats you as a bulk sender. Once you reach that level, Google says the status is permanent. Bulk senders must also:

pass both SPF and DKIM, not just one
publish a DMARC record (a policy of p=none is enough)
make sure the From domain aligns with the SPF or DKIM domain
offer one-click unsubscribe in marketing and promotional email, using the List-Unsubscribe and List-Unsubscribe-Post headers

Transactional email, such as password resets and order confirmations, doesn't need one-click unsubscribe. Google recommends acting on unsubscribe requests within 48 hours. Many email marketing platforms add these headers for you; check that yours does.

Spam complaints

Even a perfectly authenticated email goes to spam if recipients keep reporting it. Google asks senders to keep their user-reported spam rate below 0.1% and never let it reach 0.3%.

A test email can't measure this, because it depends on how real people react over time. Google's free Postmaster Tools shows your spam rate once you send enough mail to Gmail. To keep complaints down:

only email people who asked to hear from you
make the unsubscribe link easy to find
send what people signed up for, at the pace they expect

Gmail and Google Workspace are not quite the same

Personal Gmail accounts (@gmail.com) and business inboxes on Google Workspace use the same spam filtering. But Google says its sender requirements and enforcement apply to mail sent to personal Gmail accounts. For Workspace recipients, the bulk rules work more like strong recommendations, and failing mail tends to land in the Spam folder rather than bounce.

That's why our report gives a separate verdict for Gmail and for Google Workspace.

How to find out which rule you're failing

Send one email from the address and service you normally use to your private test address. The report checks SPF, DKIM, DMARC, alignment and the sender rules, then shows a verdict for Gmail, Google Workspace, Outlook.com, Microsoft 365 and Yahoo. Each failed check comes with the exact record to add or change.

Common fixes:

You use Google Workspace and DKIM is off. In the Google Admin console go to Apps → Google Workspace → Gmail → Authenticate email. Generate a DKIM key for yourbusiness.com, add the TXT record it shows at google._domainkey.yourbusiness.com, then click "Start authentication".

You have no SPF record. If Google Workspace sends your email, add this TXT record at yourbusiness.com. Keep only one SPF record; if you already have one, add include:_spf.google.com to it instead.

v=spf1 include:_spf.google.com ~all

You have no DMARC record. Add this TXT record at _dmarc.yourbusiness.com. It starts in monitoring mode (p=none), so nothing changes for your email yet. Change the rua address to a mailbox you read; once reports show all your genuine email passing, move to p=quarantine.

v=DMARC1; p=none; rua=mailto:dmarc-reports@yourbusiness.com

A marketing or CRM tool signs with its own domain. Turn on domain authentication in that tool and add every DNS record it shows. Then send another test to confirm DKIM now passes for yourbusiness.com.

After any DNS change, wait a little for it to take effect, then send a fresh test. When every check for Gmail shows a pass, the technical side is done.

Checked against: Google Workspace Admin Help, Email sender guidelines · Google, Email sender guidelines FAQ · Google Workspace Admin Help, Set up DKIM.