How to Block Emails on Outlook: Blocked Senders, Explained
To block emails on Outlook, right-click a message and choose Block > Block sender, or add the address manually under Settings > Mail > Junk email > Blocked senders and domains (Microsoft). The same settings path works in Outlook.com and new Outlook for Windows; classic Outlook uses the Junk button on the Home ribbon. One thing to know before you start: blocking does not stop the mail. It reroutes it to your Junk Email folder, and the list that powers it has a hard capacity limit.
Here is the one-sentence version: the Outlook Blocked Senders list is a per-mailbox filter that reroutes future mail from listed addresses or domains into the Junk Email folder — it does not stop that mail from being sent, accepted, or delivered.
We build unsubscribe tooling for a living, so we spend a lot of time inside mechanisms like this one. This guide covers every Outlook surface Microsoft documents clearly today, then explains where blocking stops scaling and what to use instead.
What does blocking a sender in Outlook actually do?
Blocking adds the sender's address (or their whole domain) to your Blocked Senders list. From then on, anything arriving from that address skips your inbox and lands in Junk Email (Microsoft).
Three consequences follow from that design:
- The sender is never told. Nothing bounces. They keep sending, and their mail keeps arriving — just into a different folder.
- The mail still counts against you. It still downloads, still syncs, still occupies storage until Junk auto-purges it. Microsoft removes Junk Email automatically after 14 days, and it cannot be recovered after that.
- The filter is literal. It matches the exact address or domain you listed. A sender who rotates addresses walks straight past it — more on that below.
Blocking is a per-mailbox mute button. Useful for a specific persistent nuisance. Not a strategy for a promo-heavy inbox.
How do you block emails on new Outlook and Outlook.com?
New Outlook for Windows and Outlook on the web share the same flow (Microsoft):
From a message:
- Right-click the message in your list (or open it and select the ⋯ menu).
- Choose Block > Block sender.
- Confirm. The message is removed and the address joins your Blocked Senders list.
From settings (no message needed):
- Select Settings (gear icon) > Mail > Junk email.
- Under Blocked senders and domains, select Add.
- Type the address — or just the domain, like
spammy-store.com, to block everyone who mails from it. - Select Save.
One caveat Microsoft states plainly: new Outlook does not support blocking senders for third-party accounts such as Gmail, Yahoo, or iCloud added to the app (Microsoft). For those, blocking has to happen in the provider's own settings. The block button in the Outlook window only rules the Microsoft mailbox behind it.
How do you block emails on classic Outlook?
Classic Outlook (the desktop app many workplaces still run) predates the settings-panel flow:
- Select a message from the sender you want gone.
- On the Home tab, select Junk (in some versions: right-click > Block > Block Sender).
- Choose Block Sender. Outlook confirms the address was added to the Blocked Senders list and moves the message to Junk (Microsoft).
To manage the list directly, go to Junk > Junk E-mail Options > Blocked Senders tab. From there you can add addresses and domains in bulk, edit entries, and remove mistakes.
If your mailbox lives on Exchange or Microsoft 365, the list you edit here is stored server-side and shared with Outlook on the web — block once, blocked everywhere that mailbox appears.
How do you block emails on the Outlook app (iOS and Android)?
The mobile app is the thinnest surface. There is no dedicated blocked-senders settings screen in the app itself, and the exact in-app options vary by account type. The reliable path is to manage the blocked list on the web and let the mailbox sync the result everywhere else.
The path that can appear in the app:
- Open a message from the sender.
- Tap the ⋯ menu in the top corner.
- Choose Report junk or Block sender, if your build exposes it.
Because the Blocked Senders list is stored with the mailbox, anything you block on desktop or web applies on mobile too. When mobile does not offer the option, the reliable fallback is Outlook on the web: Settings > Mail > Junk email, same as above. Manage the list there once; the phone inherits it.
How many emails can you actually block on Outlook?
This is the part most guides skip: the Blocked Senders list is finite, and Microsoft documents the caps.
| Account type | Documented cap | Source |
|---|---|---|
| Outlook.com / new Outlook | 10,000 addresses or domains across blocked and safe senders lists | Microsoft Support |
| Exchange / Microsoft 365 (classic Outlook) | 510 KB cumulative for all junk-email lists combined | Microsoft Learn |
The Exchange limit is the sneaky one. It is a size budget — measured in kilobytes, not entries — shared across Blocked Senders, Safe Senders, and Safe Recipients. Fill it and Outlook throws a blunt error: "you are over the size allowed on the server," after which the server-side junk filter is disabled entirely until you prune the lists (Microsoft Learn). Blocking your way through a heavy inbox does not just stop working. Past the cap, it switches your filter off.
Microsoft's own suggestion for people near the ceiling is to block domains instead of individual addresses (Microsoft). That helps. It does not change the underlying math: a list that holds a fixed number of names cannot keep pace with an ecosystem of senders that mints new names daily.
How do you unblock emails on Outlook?
Unblocking is the same door, walked backwards:
- New Outlook / Outlook.com: Settings > Mail > Junk email > find the address under Blocked senders and domains > Remove (the trash icon) > Save (Microsoft).
- Classic Outlook: Junk > Junk E-mail Options > Blocked Senders tab > select the entry > Remove.
Two follow-ups worth doing. First, check your Junk folder for anything the block caught — and do it promptly, since Junk purges after 14 days. Second, if the sender matters, add them to Safe Senders in the same settings panel so the filter does not re-learn the wrong lesson.
Why do blocked senders still get through?
Because the list matches strings, not senders. Microsoft's own troubleshooting page for "receiving email from blocked senders" names the two usual causes: the sender changed their address, or the address you see is not the address the mail actually came from (Microsoft).
Bulk senders rotate addresses constantly — deals@, offers@, hello@, new subdomains, new domains. Each rotation resets your block. You are playing whack-a-mole against an opponent with unlimited moles and, per the section above, a limited mallet.
This is the honest boundary of blocking: it works on senders who stand still. Legitimate-but-relentless marketing mail rarely stands still.
Should you block or unsubscribe on Outlook?
Different tools for different senders. Here is the fair comparison:
| Blocking | Unsubscribing | |
|---|---|---|
| What it does | Reroutes mail to Junk | Tells the sender to stop sending |
| Sender knows? | No | Yes |
| Mail stops arriving? | No — lands in Junk | Yes, if the sender honors it |
| Survives address rotation? | No | Yes — you leave the list itself |
| Capacity | Capped (10,000 entries or 510 KB) | Unlimited |
| Right for | Spam, scams, senders who ignore opt-outs | Legitimate newsletters and promos |
For actual spam — forged senders, scams, mail with no legitimate opt-out — block away. Never unsubscribe from true spam; our guide to stopping spam covers why.
For legitimate promotional mail, unsubscribing is the mechanism that scales, and it is less fragile than it used to be. Modern marketing mail carries a machine-readable opt-out: the List-Unsubscribe header, with one-click behavior defined in RFC 8058. Google requires it from bulk senders of 5,000 or more messages per day, with requests processed within two days. Yahoo's bulk-sender rules require the same two-day honor window. That matters even when you read the message in Outlook, because the unsubscribe mechanism travels inside the message itself.
The useful property of that header: it is client-independent. It travels inside the message, the same whether you read that message in Outlook, Gmail, or anything else. We build on exactly this mechanism — Flick (flicked.email) turns the RFC 8058 header into a one-swipe unsubscribe while you triage, the same plumbing behind Gmail's native unsubscribe button. And because "does unsubscribing even work" is a fair question, we grade real senders A–F on whether they honor opt-outs — you can look any sender up in the Exit Gap Index before deciding whether they deserve an unsubscribe or a block.
For the mechanics of doing it by hand, start with our master guide to unsubscribing, and see one-click unsubscribe explained for how the header works under the hood.
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How do I block emails on the Outlook app?
Open a message from the sender, tap the ⋯ menu, and use the junk or block option your account type exposes. For anything beyond that, use Outlook on the web: Settings > Mail > Junk email. The mobile app has no full blocked-senders management screen of its own, and mailbox-level blocks sync back to the phone automatically.
Does blocking someone on Outlook stop their emails from being delivered?
No — blocking reroutes their mail to your Junk Email folder; it does not refuse or return it (Microsoft). The sender is not notified and nothing bounces. The mail is deleted automatically after 14 days in Junk.
How do I unblock emails on Outlook?
Go to Settings > Mail > Junk email, find the address under Blocked senders and domains, select Remove, and save (Microsoft). In classic Outlook the same list lives under Junk > Junk E-mail Options > Blocked Senders. Check your Junk folder afterwards for anything the block already caught.
Is there a limit to how many emails you can block on Outlook?
Yes — Outlook.com and new Outlook cap blocked and safe senders at 10,000 combined entries, and Exchange accounts get a 510 KB size budget across all junk lists. Exceeding the Exchange budget disables the server-side junk filter until you prune the list. This is the structural reason blocking cannot be your whole strategy for a promo-heavy inbox.
Can I block an entire domain in Outlook?
Yes — in Settings > Mail > Junk email, add the bare domain (like example.com) under Blocked senders and domains, and every address at that domain is treated as junk (Microsoft). Domain blocks are the efficient way to spend your list capacity. They still will not stop a sender who moves to a new domain — for legitimate senders, unsubscribing removes you at the source.