Understanding spam and unsolicited email in Gmail

Before you read

This is an independent blog and is not affiliated with or endorsed by Google LLC.

This article on identifying and managing spam and unsolicited emails in Gmail covers personal Gmail addresses ending with @gmail.com. Information and features may differ for Google Workspace accounts or other email services.

In this article

1. Introduction
2. Part 1: Understanding spam
   1. What spam means
   2. How Gmail detects spam
   3. How Gmail shows you its decision
   4. How Gmail reads mail differently from you
   5. False positives: legitimate mail sent to spam
   6. False negatives: spam that reaches your inbox
3. Part 2: Unsolicited mail beyond spam
4. Part 3: Answers to common questions

Introduction

You've probably noticed that emails you don't want keep showing up in your inbox. Many of them are spam, but not all of them are the same kind of problem. Some messages are technically spam, sent in bulk and flagged by Gmail's systems. Others are legitimate but unwanted, like a marketing email you never signed up for. This article starts by explaining what spam is and how Gmail identifies it, then moves on to the unsolicited mail that falls outside that category, and finally covers what you can do about both.

Part 1: Understanding spam

What spam means

In the industry, spam usually means unsolicited bulk email: the same or similar messages sent to very large numbers of people who never asked for them, often to sell something, spread malware, or steal personal information. Spam is defined by how it is sent and what it is designed to do, not by how much you dislike it.

How Gmail detects spam

Gmail does not rely on a single test. It combines several layers of evidence.

The first layer is authentication. Protocols called SPF, DKIM, and DMARC help verify that a message really came from the domain it claims to come from. SPF checks whether the sending server is authorized by the domain's records. DKIM checks a cryptographic signature attached to the message. DMARC requires that the visible sender domain line up with the domains checked by SPF or DKIM, and it lets domain owners state what should happen to messages that fail.

The second layer is blocklists and sending infrastructure. Servers and IP addresses that have been used for abuse in the past can carry that reputation with them. A message can be treated with suspicion because of where it came from, even if the sender and the content look clean.

The third layer is content. Patterns in formatting, text, links, and images can resemble known spam. Excessive exclamation marks, hidden text, and links that do not match the text around them are examples of the signals involved.

The fourth layer is behavior. Gmail looks at how many people delete, ignore, or report messages from a particular sender or resembling a particular message. When large numbers of users react this way, the sender's future mail is more likely to be treated as spam.

How Gmail shows you its decision

Gmail gives you clues about the authentication results in the message itself. On the web and in the mobile app, you can see "mailed by" and "signed by" indicators that show which domains were involved. For all messages Gmail flags as spam, Gmail displays a banner above the email highlighting the reason it flagged that particular message.

Helpful information

The "mailed by" and "signed by" indicators are useful clues, but they don't prove by themselves that a sender is trustworthy. Always consider whether the message is what you would expect from that sender.

How Gmail reads mail differently from you

When you open an email, you judge it the way a person does. You look at who it's from, what it says, and whether it sounds like something you expected. Gmail's incoming spam algorithm looks at the message differently. It checks authentication signals, sending infrastructure, patterns in the formatting and links, and how many other users have deleted or reported similar messages. None of these checks asks whether the message seems reasonable to you.

That difference explains some results that can seem backward. A message that looks perfectly ordinary to you, from a familiar company with correct spelling and a clean layout, can still be sent to spam if its sending server has a poor reputation or it fails authentication. In the other direction, a message that looks obviously suspicious to you can land in your inbox because it passes the technical checks and few people have reported it. The algorithm is not reading the message the way you do, so a message's appearance is only one clue among many.

This is why the next two sections matter. Mistakes happen on both sides, and you have a part to play in correcting them.

False positives: legitimate mail sent to spam

A false positive happens when a message you wanted is sent to Spam. You can correct this in several ways:

• Move it to your inbox. Open the message in Spam and select "Not spam," or use "Move to Inbox." Gmail will usually learn from this choice.
• Add the sender to your Google Contacts. Messages from people in your contacts are less likely to be filtered as spam in the future.
• Create a filter that sends their messages to your inbox. Use the search options to enter the sender's address, then select "Never send it to Spam."
• Mark it as safe (Gmail on the web only). On some warnings, the Gmail web interface offers a "Looks safe" option. This is not available in the Gmail mobile app, so you'll need a computer to use it.

Pro tip

Adding a sender to your contacts and using a "Never send it to Spam" filter work well together for people you hear from often, such as clients or family members.

Important information

Be careful when a message comes from someone you already know. A trusted contact's account can be hacked and used to send spam, and an address can also be forged or made to look similar to a real one. If a message seems unnatural, such as an unexpected link, a request for money, or wording that doesn't sound like them, check the "mailed by" and "signed by" indicators. Then contact the person through another channel to confirm. Don't reply or open links until you've checked.

False negatives: spam that reaches your inbox

A false negative happens when spam gets past Gmail and lands in your inbox. You can help Gmail learn from it:

• Report as spam. Select the message and use the "Report spam" option. This tells Gmail that similar messages should be filtered in the future.
• Report as phishing. If the message tries to get you to share passwords, financial details, or other personal information, or pretends to be a company or person you trust, use "Report phishing" instead.

Important information

Never click links or reply with personal information in a suspicious message, even to "unsubscribe" or "verify" something. Reporting is safe, but interacting with the message can expose you.

Part 2: Unsolicited mail beyond spam

Not all unwanted email is spam. Unsolicited mail is legitimate: the sender is a real company or person, and the message follows the rules, but you never asked to receive it. Examples include marketing emails from a store you bought from once, newsletters you signed up for years ago and forgot about, and cold outreach from someone who found your address and wants to pitch you something.

Because these messages are not technically spam, they usually reach your inbox, and that is the correct behavior. Gmail cannot tell whether you want a particular marketing email, so the decision is yours. You can manage it in two ways:

• Block the sender. Open a message from them, select the More menu, and choose the option to block. Blocked senders' messages go to Spam from then on.
• Create a filter. Use the search options to define a group of messages, such as all emails from a particular sender or domain, so you can manage them together.

Pro tip

Blocking stops one sender's messages. A filter can cover a whole group, such as every message from a particular domain, so use it when a sender uses several addresses.

If an unsolicited message also looks like spam or phishing, you can use the reporting options described in Part 1: reporting as spam or reporting as phishing.

Part 3: Answers to common questions

I am an external sender, but my emails typically go into recipients' Spam. Gmail flags my emails as spam. How do I resolve it?

Successful delivery to other providers doesn't mean Gmail will treat your mail the same way. Start with Google's Email sender guidelines. Next, read the Sender requirements & Postmaster Tools FAQ, then set up Google Postmaster Tools to check your spam rate, reputation, and authentication results. Finally, use the Gmail troubleshooter for senders with email delivery issues to identify the specific cause and what to fix.

We cleaned up our domain after a hack, so why are emails still marked as spam?

Gmail does not necessarily restore delivery immediately after a security problem is fixed. First make sure the compromise has been fully contained and that your email authentication and sending infrastructure are correctly configured. Then continue sending legitimate mail and monitor your spam rate, reputation, authentication status, and delivery errors where Google Postmaster Tools provides that information.

Can Google manually whitelist our domain?

For messages being delivered to personal Gmail addresses, there is no sender-level whitelist that guarantees a domain's messages will always bypass Gmail's spam filtering and reach recipients' inboxes. Gmail evaluates incoming messages using its own filtering systems.

Why are our emails landing in category tabs like "Promotions" or "Updates"?

Category tabs are part of the normal inbox, not Spam. Recipients can move your email to their Primary tab by dragging the message over and clicking "Yes" when Gmail asks to apply it to future emails. Being placed in a category does not mean Gmail considers the message to be spam.

Our messages to Gmail are bouncing back and not delivering at all.

Check the bounce-back message for the SMTP response code and the accompanying error text. These details can help identify whether the problem involves authentication, sender reputation, policy requirements, message content, or another delivery issue. Use Google's troubleshooting resources to investigate the error and determine the appropriate next step.

Why did Gmail suddenly start marking emails from our domain as spam?

A sudden change in spam filtering can have several possible causes, including changes in sending volume or behavior, authentication problems, message content, sender or domain reputation, recipient spam reports, or changes in the way the sending infrastructure is configured. Check Google Postmaster Tools when data is available and look for changes in spam rate, reputation, authentication, or delivery errors. Also consider whether anything recently changed in your email system, domain configuration, or sending practices.

Why do I still get marketing emails after I unsubscribe?

Start by checking whether you actually subscribed. In Gmail on the web, open Manage subscriptions to see the mailing lists you have signed up for. If you willingly subscribed and then unsubscribed, Gmail sends further messages from that sender to Spam. If you don't recognize the subscription, the mail is probably unsolicited rather than spam, so use the block and filter options described in Part 2.

Why am I getting spam that appears to come from my own address?

Spammers can forge the From address, so a message can appear to come from your own account. This doesn't mean your account has been hacked. Check the "mailed by" and "signed by" indicators, and read the banner at the top of the message. Don't reply or open any links.

About the author

Somnath Datta has helped users with Gmail and Google Account recovery in the Google Help Community since 2012. A Diamond Product Expert and Mentor for both the Gmail and Google Account Help Communities, he also writes practical guides on Gmail and Google Account topics. Read more of his work on his Google Help Community profile.

Last reviewed: October 28, 2026