An unfamiliar name shows up in the inbox, and the first instinct is to stop it from happening again.
Both Gmail and Outlook let you block a specific sender, which routes their future messages into Spam or Junk Email instead of the inbox. Neither service has one switch that blocks every unknown sender at once — blocking works address by address, or domain by domain.
This article walks through how to block unknown senders in Gmail and Outlook on phones and computers, how to undo a block, and what to do if a blocked message still slips through.
Contents
- What Blocking Actually Does
- How to Block a Sender in Gmail
- How to Block a Sender in Outlook
- Blocking a Domain vs. a Single Address
- How to Unblock Someone
- If Blocked Messages Still Show Up
- Things to Watch Out For
- Frequently Asked Questions
🔍 What Blocking Actually Does
Before blocking anyone, it helps to understand what the feature actually changes.
Blocking a sender in Gmail or Outlook does not stop that person or company from sending mail. It also will not notify them that they have been blocked.
What changes is where their messages land. In Gmail, future messages from a blocked address go straight to Spam. In Outlook, they go to Junk Email. The message still technically arrives; it is just routed out of the main inbox.
This distinction matters for anyone expecting blocking to work like it does on a phone, where a blocked caller cannot get through at all. Email blocking is a filtering action, not a wall. Blocking redirects mail, it does not prevent it from being sent.
It is also worth knowing that unknown sender is not an official category in either service. There is no single toggle labeled something like block all strangers. If the goal is to screen out everyone not already in your contacts, that calls for filters or junk-mail settings rather than one-by-one blocking, which is better suited to specific repeat offenders.
💡 Key point: Blocking targets one address or domain at a time and sends future mail to Spam or Junk — it does not stop the sender from mailing you.
⚙️ How to Block a Sender in Gmail
Gmail keeps the blocking option in the same place across most versions of the app, tucked into the three-dot menu next to the reply button.
On a phone, open the Gmail app and open the message from the sender you want to block.
- Tap More (the three dots ⋮) next to Reply.
- Tap Block [sender].
- Confirm when prompted.
This works the same way on both iPhone and Android — the menu wording and icon position are consistent, though exact spacing can shift slightly between app versions.
On a computer, the flow mirrors the mobile steps closely.
- Open the message in Gmail.
- Click More (⋮), next to Reply.
- Click Block [sender].
Once blocked, any new message from that address routes to Spam automatically. Gmail does not retroactively move older messages already sitting in the inbox — only future mail is affected.
For newsletters or promotional senders that are not actually malicious, Gmail notes that Unsubscribe is often a better fit than blocking, since it stops the mail at the source instead of just rerouting it.
If a message looks suspicious — a phishing attempt or a scam — use Report spam instead of, or in addition to, blocking. Reporting spam helps Gmail’s filters flag similar messages more broadly, while blocking only affects that one address.
📱 How to Block a Sender in Outlook
Outlook’s blocking tools live in slightly different places depending on whether you use Outlook.com, the new Outlook on the web, or classic Outlook for Windows.
For Outlook.com or the new Outlook on the web, the setting sits inside the junk email controls.
- Select Settings (the gear icon) → Mail → Junk email.
- Under Blocked senders and domains, select Add blocked sender.
- Enter the email address — or a domain if blocking every address at that domain — then select OK and Save.
There is also a shortcut directly from a message: open or right-click it, then choose Block → Block Sender. The exact wording can vary by account type and update version.
Classic Outlook for Windows uses the ribbon instead of a settings menu.
- Select a message from the sender you want to block.
- Go to Home → Junk → Block Sender.
- To review or edit the full list later, go to Home → Junk → Junk E-mail Options → Blocked Senders.
Blocked senders in Outlook have their messages moved to the Junk Email folder going forward, similar to how Gmail handles Spam.
One important limitation: Microsoft states that the new Outlook does not support sender blocking for some third-party accounts, such as Gmail accounts added to Outlook. If that applies, block the sender through the original email provider’s own tools instead of trying to do it from inside Outlook.
If the menu described here does not match what appears on screen, search for Junk or Blocked in the Outlook settings search bar — Microsoft updates the interface periodically, and renamed menus are easier to find that way than by hunting through every tab.
Because blocking touches account-level mail settings, it is a good idea to check Outlook’s official help page or contact support directly if an unusual account type or business email setup behaves differently than expected.
🛡️ Blocking a Domain vs. a Single Address
Both services allow blocking at the domain level, not just the individual address, but the two approaches serve different purposes.
Blocking a single address — something like name@example.com — only affects mail from that exact address. If the same company or person emails from a different address at the same domain, those messages still reach the inbox normally.
Blocking an entire domain, such as example.com, affects every address at that domain. This is useful when a company sends from many rotating addresses, but it comes with real risk: it can also catch legitimate senders who happen to share that domain, including coworkers at a shared business domain or multiple departments at the same organization.
| Approach | What It Affects | Best Used When |
|---|---|---|
| Block single address | Only that exact email address | One specific sender is the issue |
| Block entire domain | Every address ending in that domain | You are certain no legitimate mail comes from that domain |
In Outlook, domain blocking is entered the same way as a single address under Blocked senders and domains — the system treats a domain entry (without a specific username) as covering the whole domain.
Use domain blocking only when confident that nothing from that entire domain is worth receiving, since there is no simple way to carve out one address as an exception once the whole domain is blocked.
✅ How to Unblock Someone
Blocks are not permanent, and both services make it possible to reverse one if a legitimate sender gets caught by mistake.
In Gmail on a computer, go to Settings → See all settings → Filters and Blocked Addresses. Find the sender in the list and choose Unblock selected addresses.
On a Gmail mobile app, open a message from the blocked sender (it will be sitting in Spam) and tap More → Unblock [sender].
In Outlook, the reverse process depends on the version in use.
- For Outlook.com or new Outlook on the web: go to Settings → Mail → Junk email, find the entry under Blocked senders and domains, and remove it.
- For classic Outlook for Windows: go to Home → Junk → Junk E-mail Options → Blocked Senders, select the address, and remove it from the list.
After unblocking, new messages from that sender should return to the regular inbox, though any messages already sitting in Spam or Junk may need to be moved manually — unblocking does not automatically restore past messages to the inbox folder.
⚠️ If Blocked Messages Still Show Up
Occasionally a blocked sender’s messages keep appearing in the inbox, and there are usually a few explainable reasons.
The most common cause is address mismatch. If a sender’s address changes even slightly — a different domain, a new account, a slightly altered username — the old block will not catch the new address, since blocking works on exact addresses or domains rather than on a person’s identity.
Another cause is checking the wrong account. If multiple Gmail or Outlook accounts are in use, a block applied in one account has no effect on mail arriving in a different one, even if both show up in the same mail app.
In Gmail, double-check the block by going to Settings → See all settings → Filters and Blocked Addresses to confirm the exact address listed. In Outlook, review the Junk Email settings and the Blocked Senders list the same way.
⚠️ Watch out: A block only matches the exact address or domain entered — small changes to the sender’s address, or checking the wrong account, are the most common reasons a block does not seem to work.
For messages that look like scams or phishing rather than simple annoyances, blocking alone is not the strongest tool. Gmail’s Report spam and Outlook’s Report junk both flag the message content more broadly, which can help beyond just that one address.
📌 Things to Watch Out For
A few practical cautions make blocking more effective and reduce accidental mistakes.
Avoid opening links or attachments in suspicious messages before deciding whether to block or report them. Blocking only changes where future mail from that address lands — it does nothing to neutralize a message already opened.
Be cautious with domain-level blocks on shared or business domains. Blocking an entire domain can unintentionally filter out legitimate contacts who happen to share that same email domain, such as coworkers or vendors.
For frequent promotional mail or newsletters that are not malicious, Unsubscribe (in Gmail) is often the more effective long-term fix, since blocking a legitimate sender just reroutes their mail rather than stopping it.
Since blocking settings sit alongside account security and spam-filtering options, it is worth checking the official Gmail or Outlook help pages, or contacting their support channels, for details specific to an account type that behaves unexpectedly.
🙋 Frequently Asked Questions
Q. Can blocking a sender stop them from emailing other accounts?
No. Blocking only affects what happens to mail arriving in the account where the block was set up. It has no effect on the sender’s ability to email anyone else.
Q. Does blocking delete past messages from that sender?
No. Blocking only affects future messages. Past messages already in the inbox stay where they are unless manually moved or deleted.
Q. Will the sender know they have been blocked?
Neither Gmail nor Outlook notifies a sender that they have been blocked. Their messages simply stop reaching the inbox and are rerouted to Spam or Junk instead.
Q. Is there a way to block every sender not already in contacts?
Not as a single built-in toggle in Gmail or Outlook. That kind of broad screening is closer to filter-based rules than to the direct blocking feature covered here.
Q. Why does new Outlook not let me block a Gmail account I added?
Microsoft states that new Outlook does not support sender blocking for some third-party accounts, including Gmail accounts connected to it. In that case, set up the block directly in Gmail instead.
Q. What happens if I block a domain by mistake?
Go back into the blocked senders list — Filters and Blocked Addresses in Gmail, or Blocked senders and domains / Blocked Senders in Outlook — and remove the domain entry to restore normal delivery.
Q. Should I block or report a phishing email?
Reporting is generally more useful for phishing or scam attempts since it flags the content more broadly, while blocking only manages that one address going forward. Using both is reasonable when a message looks like a scam.
Quick Summary
| Item | Details |
|---|---|
| Gmail block (mobile) | Open message → More (⋮) → Block [sender] |
| Gmail block (desktop) | Open message → More (⋮) → Block [sender] |
| Gmail blocked mail goes to | Spam folder |
| Outlook.com block | Settings → Mail → Junk email → Add blocked sender |
| Classic Outlook block | Home → Junk → Block Sender |
| Outlook blocked mail goes to | Junk Email folder |
| Unblocking | Gmail: Filters and Blocked Addresses; Outlook: Blocked Senders list |
A reasonable first step is opening one unwanted message right now and using the Block option in whichever app is in use, then checking the Spam or Junk folder afterward to confirm it landed correctly.
This article is based on public information available at the time of writing. Menus and steps may change with app or device updates.