Is Gmail filtering my emails and how do I tell and fix it?

Why is Gmail sending my emails to spam?

Gmail's spam filter weighs three families of signal, and a weakness in any one can push you to the Spam folder:

1. Authentication. If Gmail cannot verify that you are authorized to send for your domain, it distrusts the message. You need SPF or DKIM to pass and align with your From: domain, plus a DMARC record. A message that fails all authentication is a prime spam candidate, and it is the most common fixable cause.
2. Reputation. Every sending domain and IP carries a reputation score with Gmail based on past behavior: complaint rates, spam-trap hits, and how much of your mail users delete unread. New or dormant domains have no reputation, which Gmail treats cautiously until you build one by warming up the domain.
3. Engagement and content. If recipients rarely open your mail, mark it as spam, or you send to addresses that no longer exist, Gmail learns your mail is unwanted. Spam-trigger content (deceptive subject lines, link shorteners, mismatched display names) compounds it.

The order matters: fix authentication first because it is binary and within your control, then reputation and engagement, which take time.

When the symptom affects a sending stream rather than one message, the Gmail spam filter sender guide orders DNS, delivered-header, Postmaster, and same-path retest evidence without claiming to expose Google's private classifier.

How do I check what Gmail sees about my domain?

Two tools show you Gmail's own view, and you should use both:

• Google Postmaster Tools. Register and verify your sending domain at postmaster.google.com, and after a day or two of volume it reports your domain reputation, IP reputation, spam-complaint rate, and authentication pass rates for SPF, DKIM, and DMARC. A "Low" or "Bad" reputation, or a spam rate creeping toward Google's 0.3% ceiling, tells you exactly why you are being filtered.
• The received message headers. Send a test to a Gmail account you control, open the message, and choose "Show original." Read the Authentication-Results line: spf=pass, dkim=pass, and dmarc=pass are what you want. Our Email Header Analyzer parses that header for you, and why Gmail reports an SPF error covers the most common failure.

Between the two, Postmaster Tools tells you whether Gmail trusts you and the headers tell you why a specific message passed or failed.

What are Gmail's requirements for senders?

Since early 2024 Gmail has enforced a baseline for anyone sending in volume, and meeting it is no longer optional:

• Authenticate every message with SPF and DKIM, and publish a DMARC record (at minimum p=none) that aligns with your From: domain.
• Keep spam complaints low. Google's guidance is to stay under a 0.3% user-reported spam rate, and ideally below 0.1%.
• Support one-click unsubscribe (the List-Unsubscribe header) on bulk marketing mail.
• Send from a domain with valid forward and reverse DNS (a PTR record) on your sending IP.

Bulk senders (roughly 5,000+ messages a day to Gmail addresses) that miss these are filtered to spam or rejected. Smaller senders are held to a softer version of the same bar. You can see the official list on Google's Email sender guidelines. Run the Email Security Score to check where your domain stands against them in one pass.

Common issues with Gmail filtering

My email authenticates but still goes to spam

Passing SPF and DKIM is necessary, not sufficient. If your domain reputation is low (because of past complaints, a spam-trap hit, or a cold domain) Gmail can filter authenticated mail anyway. Check Postmaster Tools for reputation, prune invalid addresses from your list, and give a cold domain time to warm. Authentication opens the door; reputation decides which folder you land in.

Only some recipients see my mail in spam

Gmail personalizes filtering. A recipient who has never interacted with you, or who once deleted your mail unread, may see it filtered while an engaged recipient gets it in the inbox. This is expected. The fix is list-level, not per-recipient: improve overall engagement, remove chronically unengaged contacts, and never buy lists.

My mail lands in the Promotions tab, not Spam

That is categorization, not filtering, the message was delivered to the inbox. Gmail sorts bulk, image-heavy, or marketing-shaped mail into the Promotions tab by design. For genuine one-to-one and transactional mail, plain-text-leaning formatting and a clean sending reputation help it reach the primary tab, but you cannot force a category.

Gmail suddenly started filtering mail that used to deliver

A sudden change usually means a reputation event: a spike in complaints, a compromised account sending spam from your domain, or a new sending service you added without authenticating it. Check Postmaster Tools for a reputation drop and audit every service that sends as your domain. A single unauthenticated stream can drag the whole domain down.

Evidence

Sources and further reading

• Google: Email sender guidelines
• Google: Get started with Postmaster Tools
• Microsoft: Email authentication in Microsoft 365, for the Outlook side of the same checks

Where Palisade fits

Most Gmail filtering traces back to an authentication or alignment gap on one of the domains or services you send from, and those are easy to miss when mail is spread across a CRM, a help desk, and a marketing platform. Palisade deploys and monitors SPF, DKIM, and DMARC across every sending source, reads your aggregate DMARC reports to catch a stream that is failing or unsigned, and flags reputation-damaging misconfigurations before Gmail acts on them. Start with the Email Security Score to see what Gmail sees about your domain today.

Related reading

• Why are my emails landing in spam and how can I fix it?
• Why is my email going to spam in Outlook but not Gmail?
• Why am I not receiving emails? How to troubleshoot