To block spam emails on Outlook, open Settings > Mail > Junk email, type the address under Blocked senders, and select Add. To kill an entire domain in one go, put it under Blocked domains instead. Blocked mail lands in your Junk Email folder, not the bin. Classic Outlook on the desktop keeps the same list under Home > Block > Junk E-mail Options.
That domain field is the reason this guide is shorter than the Gmail one. Outlook gives you free, native, one-line domain blocking. Gmail gives personal accounts none at all, and Yahoo charges for it. If spam is arriving from fifteen addresses at the same domain, Outlook is the only one of the three where the fix takes ten seconds.
What Outlook takes back, it takes back in confusion. There are two desktop clients with different menus, a web client, and a mobile app, and the click path is different in each. Classic Outlook also ships with its junk filter set to do nothing, which surprises most people. Both of those are covered below.
Blocking still works one address at a time, and a spam operation mints new addresses faster than you can add them. That's the gap SecondInbox covers: a free temporary inbox in one click, no registration, permanently deleted when it expires. Use it for the free trial, the discount code, the app you'll open twice, the whitepaper that wants an email first. A sender who never gets your Outlook address is a sender you never have to block.
What blocking on Outlook actually does
Microsoft's own wording, from Block or unblock senders in Outlook: a blocked sender's message is "immediately moved to the Junk Email folder." Moved. Not deleted.
That puts Outlook in the same place as Gmail and well short of Yahoo, which throws blocked mail away on arrival with no copy kept anywhere. The middle ground is the right call. You get a window to notice you blocked the wrong retailer before the evidence disappears.
How long that window lasts is genuinely unclear, and not because the answer is hard to find. Two current Microsoft support pages give different numbers. The block and unblock article says email "is automatically removed from the Junk Email folder after 14 days and can't be recovered after that." Filter junk email and spam in Outlook says junk "is retained for 30 days before it is automatically deleted and is not recoverable." Both are live. Neither acknowledges the other.
Assume 14 days and you'll never be wrong in a way that costs you. Treat the Junk folder as a holding pen with a short lease, not an archive.
Two more things follow from how the block is built.
The sender learns nothing. No bounce, no failure notice, nothing. Their system records a successful delivery and they keep sending, because from where they sit nothing happened. Blocking is the only action in this guide that costs the sender absolutely zero.
The list is finite, and the ceiling moves depending on where you are. Microsoft's block and unblock article says you can hold "up to 10,000 addresses or domains in the blocked senders and safe senders lists." Classic Outlook's junk filter overview puts the Safe Sender limit at 1,024. Either way it's a fixed number of slots, and a spam operation mints fresh addresses faster than you can spend them.
Use the block for a specific, persistent, single-address nuisance. For anything bulk, the next three sections are better tools.
How to block spam emails on Outlook
In new Outlook, Outlook on the web, and Outlook.com
These three share a UI, so the path is the same in all of them:
- Open the message from the sender you want gone.
- Select the three-dot More options menu on the message toolbar.
- Choose Block > Block sender.
- Confirm.
To add an address without having a message in front of you, go to Settings (the gear icon) > Mail > Junk email, type it under Blocked senders, and select Add.
In classic Outlook on Windows
Right-click the message, then select Block > Block Sender. The full options panel is at Home > Block > Junk E-mail Options, on the Blocked Senders tab.
Worth knowing which client you're in before you go looking for menus that aren't there. Microsoft began the opt-out phase of the new Outlook rollout in April 2026, so new Outlook is now the default for most people, while classic Outlook stays supported until at least 2029 on perpetual and desktop-app subscription licences. Plenty of people are still moving between the two and wondering why the instructions they found don't match their screen.
In the Outlook mobile app
Open the message, tap the three dots in the top right, tap Report junk, then choose Block sender.
As with Gmail, mobile is add-only. Reviewing or cleaning up the blocked list means going to the web or the desktop client.
Where the blocked list lives
Settings > Mail > Junk email on new Outlook and the web. Home > Block > Junk E-mail Options in classic Outlook. Both screens let you remove entries as well as add them.
Open it once a year. Most people have blocked something they now want mail from and have zero memory of doing it.
Outlook's domain block is the best of the big three
This is the one place Outlook clearly beats its competitors, and hardly anyone uses it.
Go to Settings > Mail > Junk email, find Blocked domains, type spammydomain.com, and select Add. Everything from every address at that domain goes to Junk from then on. One entry, whole domain, no subscription.
Line that up against the others and the gap is obvious. Gmail's personal accounts have no domain block whatsoever, so you have to build a filter with *@domain.com in the From field to fake one. Yahoo has real domain blocking but puts it behind a Yahoo Mail Plus subscription. Outlook just gives it to you.
Classic Outlook adds a genuinely obscure version of the same idea. Under Junk E-mail Options > International, the Blocked Top-Level Domain List blocks mail by country code, and Blocked Encodings List blocks messages in specific character sets. Both are blunt instruments. Blocking an entire country's TLD to stop one sender will eventually eat something you wanted, so reach for them only when the spam is overwhelmingly concentrated and you know what you're giving up.
One limit applies to every tool here, domain block included: it can't catch a domain you haven't met yet. That's the permanent shape of this problem. Every button on this page reacts to a sender who already has your address.
Classic Outlook ships with its junk filter switched off
Here's the fact that reframes most people's Outlook spam problem. Straight from Microsoft's junk filter overview: "By default, the Junk Email Filter is turned on and the protection level is set to No Automatic Filtering."
Read that twice. The filter is on, and it's set to filter nothing automatically. At that level the only thing standing between you and a spammer is the blocked list you typed by hand. If you've been running classic Outlook thinking Microsoft's spam detection was quietly working in the background, it wasn't.
Fix it at Home > Block > Junk E-mail Options > Options. Four levels, in Microsoft's own descriptions:
- No Automatic Filtering turns off the automatic filter, though "messages are still evaluated by using the domain names and email addresses in your Blocked Senders List."
- Low filters "only the messages that are the most obvious junk."
- High is for when you "receive lots of junk messages," and will need you to check the Junk folder for false positives.
- Safe Lists Only is "the most restrictive option." Anything not from your Safe Senders or Safe Recipients list gets classified as junk.
Low is the right default for almost everyone. High is worth it if you're drowning, as long as you actually check Junk. Safe Lists Only is an allowlist, and it will silently eat mail from every new correspondent you have, including the shipping notice from a shop you just ordered from.
On the same screen sits the worst checkbox in Outlook: Permanently delete suspected junk email instead of moving it to the Junk E-mail folder. Leave it alone. It turns every false positive into a message you will never see, never find, and never know existed. Junk email that's merely inconvenient to scroll past is a far better outcome than a two-factor code that quietly evaporated.
None of this applies to Outlook.com, new Outlook, or the web client. Those run Microsoft's server-side filtering, which is on and working without any configuration from you.
Report junk beats Block, and Sweep beats both
Your blocked list is a private note to yourself. Reporting is a complaint on the sender's permanent record.
Select the message and hit Report > Report junk. Outlook files future mail from that sender under Junk and feeds the signal into Microsoft's classifier, so similar mail from senders you've never seen gets caught too. Moving something out of Junk with Not junk trains it the other way, and that half matters more than people credit. A filter over-trained into eating your bank's mail is a worse problem than the spam was.
Reporting costs the sender real money at Microsoft, and since 2025 the stakes went up. Under Microsoft's requirements for high-volume senders, anyone sending more than 5,000 messages a day to Outlook.com, Hotmail.com, or Live.com addresses must pass SPF, DKIM, and DMARC. Since May 5, 2025, mail that fails those checks isn't filed in Junk. It's rejected outright. Microsoft went further than Gmail and Yahoo here: those two throttle and junk non-compliant bulk mail, Outlook refuses it at the door.
Then there's Sweep, which has no equivalent at Gmail or Yahoo and is badly underused. Select a message from the offending sender and hit Sweep in the toolbar. The options, per Microsoft's documentation, let you "automatically delete all incoming email from a particular sender, to keep only the latest email, or to delete email older than 10 days."
That first option is the one to know. Blocking handles the next message. Sweep handles the next message and the 400 already sitting in your inbox from the last two years, in one action. Two caveats: sweep rules run once a day rather than on arrival, and Sweep isn't available in Junk Email, Drafts, Sent Items, or Deleted Items.
The split I'd use:
- Report junk for anything genuinely unsolicited. It's the only option that improves over time.
- Sweep when a sender has a backlog in your inbox, not just a future.
- Blocked domains for a whole domain.
- Block for the one persistent sender who keeps using one address.
A lot of what you're blocking, you signed up for
A retailer you bought running shoes from in 2023, emailing you five times a week, entirely legally, because you handed over your address at checkout. That isn't spam and blocking is the wrong tool for it.
Outlook sorts a chunk of this on its own. The Focused and Other split keeps bulk mail out of your main view without any list maintenance, and messages that qualify carry a one-click Unsubscribe link at the top of the message.
One hard rule on that link, and it's the same rule in every client: only unsubscribe from mail you actually signed up for. Clicking unsubscribe on real spam confirms your address is live and read by a human, which is the single most valuable thing you can hand a spam operation. If you don't remember giving them your address, report it as junk instead. We went through the reasoning in why you shouldn't unsubscribe from newsletters you never signed up for.
Outlook aliases are useful, and they're not disposable addresses
Outlook.com lets you add alias addresses to your account, which sounds like the answer to all of this. It's a good feature. It's also frequently misunderstood, and the misunderstanding is expensive.
Microsoft's own definition is the important part: "An alias is an additional email address associated with your Outlook.com account. An alias uses the same inbox, contact list, and account settings as your primary email address." And: "You can sign in to your Outlook.com account with any alias, they all use the same password."
Same inbox. Same password. Same account. An alias is a second door into the house you already live in, so if one gets sold to a list broker, the mail still arrives in the inbox you read every day. Killing the alias is the fix, and that's a real fix, but it's cleanup after the fact rather than separation.
The practical terms, based on what Microsoft's support answers report: roughly 10 aliases total, with no more than 2 added in any 7 day window and 10 in a rolling year. You can't create new @hotmail.com, @live.com, or @msn.com addresses, and deleting a Microsoft-domain alias destroys it permanently. Ten addresses, rationed two a week, is enough for the accounts you intend to keep. It isn't enough to spend one on every signup form you meet.
That's the actual distinction, and it's the same one as Yahoo's disposable addresses. An alias forwards into the account you already have and lives until you kill it, which is right for something you'll keep. A temporary inbox is a separate mailbox with an expiry date and no link back to you, which is right for a signup you'll never revisit. Different jobs. We compared the two models properly in temporary email vs alias forwarding.
The fix blocking spam emails can't do
Nothing above pulls your address back off a list. Blocking, domain blocking, sweeping, reporting, and unsubscribing all react to an address that's already circulating. If your Outlook address turned up in a breach, it's being resold right now, and no amount of list maintenance touches that.
The habit that compounds is dull: keep your Outlook address for the short list of things you'd hate to lose, and use a disposable one for everything else.
A disposable inbox is a real inbox with an expiry date. You get an address instantly, receive the confirmation mail, click the verification link, and walk away. When it expires, the contents are deleted from the server. If that address shows up on a resold list in 2029, there's nothing at the other end of it.
The honest limits, because this isn't magic:
- Some sites reject known disposable domains at signup. Banks and the big platforms usually do. If you need the account long term, use your real address.
- The inbox has to outlive the verification email. Ten-minute services get tight when a confirmation takes twelve, which is why one click extends a SecondInbox inbox instead of making you start over.
- Never use a disposable address for anything you'll need to recover. No password reset survives an expired inbox.
Which is what SecondInbox is for. One click, an inbox, no account, no personal details, everything deleted from our servers when it expires. Register free if you'd rather hold several addresses across sessions. If most of your Outlook spam traces back to free trials and one-off signups, changing that one habit does more over six months than any block list will. For the general case and the other clients, start with how to block spam emails, and the two guides worth reading beside this one are how to block spam emails on Gmail and how to block spam emails on Yahoo.
No. It stops the mail reaching your inbox, but the sender keeps sending. Outlook moves the message to Junk Email and sends no bounce back, so they have no idea anything changed and no reason to stop.
In new Outlook, Outlook on the web, and Outlook.com it's at Settings > Mail > Junk email. In classic Outlook it's at Home > Block > Junk E-mail Options, on the Blocked Senders tab. You can add and remove entries from either screen, but not from the mobile app.
Yes, and it's free. Go to Settings > Mail > Junk email, enter the domain under Blocked domains, and select Add. Every address at that domain goes to Junk. This is Outlook's clearest advantage over Gmail, which has no domain block on personal accounts, and Yahoo, which charges for one.
Microsoft's own support pages disagree. The block and unblock article says 14 days, while the junk email filter article says 30. Assume 14 and check the folder every couple of weeks, because deleted junk isn't recoverable either way.
If you're on classic Outlook for Windows, the Junk Email Filter defaults to No Automatic Filtering, meaning it only acts on the blocked list you typed yourself. Change it at Home > Block > Junk E-mail Options > Options. Low is the sensible setting. Outlook.com and new Outlook filter server-side and need no setup.
The take
Outlook hands you the best domain block of the big three providers and then buries it in a settings screen nobody opens. Use it. One entry kills a whole spam domain, which is worth more than fifty individual blocks, and Sweep clears the backlog those fifty blocks would leave sitting in your inbox.
If you're on classic Outlook, change the filter level today. Shipping with No Automatic Filtering as the default means a lot of people have been fighting spam by hand while assuming a filter had their back.
Then fix the intake, because none of it stops the next list you land on. Every address you type into a signup form is a spam problem on a delay. Type one you don't mind losing.
