How to Stop Spam Emails: Why You Get Them and How to Block Them in Gmail and Outlook

To stop spam emails, you need to work on two fronts: clean up what's already arriving (report it as spam, block senders, and create filters) and keep your address from landing on new lists (only share it where it's truly needed, and use a secondary or temporary email for one-off sign-ups). No method gets rid of spam completely, but by combining both, you can keep your main inbox almost spotless.

Why am I getting so much spam?

You get spam because your address is on one or more lists that spammers buy, sell, or build themselves. According to INCIBE (2018) and Malwarebytes, the most common ways it gets there are:

• Data breaches: someone hacks a store, forum, or service you signed up for and publishes or sells the user database.
• Sign-ups and sold lists: some sites share or sell the addresses of people who sign up for promotions or newsletters.
• Scam sites: fake online stores or giveaways that exist only to harvest email addresses.
• Published addresses: automated bots crawl websites, forums, and public profiles looking for anything that looks like an email address.
• Chain emails: forwarded messages sent without BCC that expose every recipient's address.
• Malware and guessed combinations: malicious software that steals address books, and attacks that try common names on popular email domains.

If you want to check whether your address has shown up in a data breach, see our guide to email privacy.

What should I do with the spam I'm already getting?

Report it as spam instead of just deleting it: that way your provider's filter learns to recognize similar messages. In Gmail, select the message and click Report spam at the top. In Outlook, use the option in the message toolbar to mark it as junk.

On top of that:

• Don't reply. Replying confirms the address is active and that someone reads it.
• Don't open links or attachments. A link can lead to a fake page, and an attachment can contain malware. Gmail Help recommends not replying or clicking links unless you're sure the sender is trustworthy.
• Block the sender if they keep at it. In Gmail, open the message, click More (next to Reply), and choose Block followed by the sender's name; their future emails will go to Spam.
• Block external images. This keeps a tracking pixel from telling the sender you opened the message.

When is it actually a good idea to unsubscribe?

Unsubscribing only makes sense when you recognize the sender and know you signed up yourself, for example a store you bought from or a newsletter you requested. In those cases the company usually honors the request, and it's the fastest way to cut down on marketing emails. Gmail Help notes that if you subscribed and no longer want those emails, you can use the Unsubscribe option shown in the message.

With emails you don't recognize, don't do it. INCIBE (2018) warns that cybercriminals use unsubscribe attempts to confirm an account is active, which leads to even more spam. In those cases, report the message as spam and delete it. For marketing from brands you do know, we have a guide on how to stop promotional emails.

How do I create a spam filter in Gmail?

A Gmail filter automatically applies an action to emails that match certain criteria, such as a sender or words in the subject line. According to Gmail Help, these are the steps on the web version:

1. Open Gmail on your computer.
2. In the search box at the top, click the Show search options icon.
3. Enter your criteria: for example, the sender's domain in From or a word that keeps showing up in Subject.
4. If you want to check which emails match, click Search.
5. Click Create filter.
6. Choose the action: delete it, archive it, apply a label, star it, or forward it.
7. Click Create filter again to save it.

Review your filters under Settings > See all settings > Filters and Blocked Addresses: a filter that's too broad can send emails you actually wanted straight to the trash.

How do I block senders and create rules in Outlook?

In Outlook.com you can block an address or an entire domain from your settings. According to Microsoft:

1. Select Settings at the top of the page.
2. Go to Mail > Junk email.
3. Under Blocked senders and domains, choose to add a blocked sender and enter the address or domain.
4. Save your changes.

In the same section, Safe senders and domains does the opposite: it keeps a sender you care about from ending up in your Junk Email folder. Keep in mind that Outlook keeps messages in that folder for 30 days and then deletes them permanently, with no way to recover them.

For more specific cases, use rules. In Outlook.com, go to Settings > Mail > Rules, select Add new rule, give it a name, add at least one condition (for example, the sender contains a certain domain) and one action (move it to a folder or delete it), and save. In the new Outlook for Windows, you can also right-click a message, choose Rules > Create rule, and select More options for additional settings. Microsoft notes that the new Outlook doesn't support rules for third-party accounts like Gmail or Yahoo; for those, set the rules up with the provider.

How do I keep my email off more lists?

The most effective prevention is not handing out your main address on sign-ups that don't need it. Save your personal email for banks, work, official paperwork, and people you trust, and use a different address for everything else.

For one-time sign-ups that only ask you to confirm your email, a temporary email keeps your real address out of yet another database. If you're not sure how it works, start with what a temporary email is. With a free Mawlio account, you can have two free 1-hour addresses at the same time, and when the hour is up you can request another. For free trials, see how to sign up without flooding your inbox; just note that creating multiple accounts to repeat the same trial usually violates a service's terms, and we don't recommend it.

There's one limitation you should know about: a temporary address that expires can later be assigned to someone else. That person starts with an empty inbox, but they would receive any new email sent to it, including a password reset. So don't use one for accounts you'll ever need to recover, like banking, shopping, or official paperwork.

What's the difference between spam, phishing, and legitimate marketing?

Spam is any bulk email you didn't ask for; phishing is a type of fraud that impersonates a company or person you trust to steal your information; and legitimate marketing comes from a brand you gave your email to. According to the FTC (2022), phishing messages often arrive unexpectedly, mention suspicious activity or a problem with a payment, and ask you to click a link or confirm personal information.

Frequently asked questions

Why am I getting spam if I never gave out my email?

Your address may have ended up on a list through a data breach at a service you used years ago, because it was published on a web page, or because someone included it in a chain email without using BCC. There are also programs that try combinations of common names on popular email domains.

Is opening a spam email dangerous?

The main risk comes from clicking links, downloading attachments, or loading images that tell the sender you opened it. If you block external images and don't interact with the content, you greatly reduce that risk.

Does reporting spam help if it keeps coming?

Yes. Reporting messages helps your provider's filter learn. If a sender keeps at it, block them or create a filter or rule that deletes their emails automatically.

Does a temporary email help stop spam?

It keeps one-off sign-ups out of your personal inbox. It doesn't work for accounts you'll need to recover, because the address expires and can be reassigned to someone else.

If you want to keep your one-time sign-ups separate from your main inbox, you can get a free address on Mawlio, no sign-up required.

Sources

• INCIBE, Antispam email filters: what they're for and how to set them up (2018) (in Spanish)
• Malwarebytes, How to stop spam emails
• Google, Gmail Help: Create rules to filter your emails
• Google, Gmail Help: Block or unblock a sender
• Google, Gmail Help: Mark or unmark Spam in Gmail
• Microsoft, Filter junk email and spam in Outlook
• Microsoft, Manage email messages by using rules in Outlook (in Spanish)
• FTC, How to recognize and avoid phishing scams (2022) (in Spanish)