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How to Block an Email Address or IP in Gmail, Outlook, and More

Learn how to block unwanted email addresses and IP addresses in Gmail, Outlook, Yahoo, and at the server level. Stop spam and unwanted senders for good.

Last updated: 2026-02-06

Unwanted email is more than annoying. Spam wastes your time, phishing puts your data at risk, and persistent senders clutter your inbox. The fix is simple: block them.

This guide walks you through how to block an email address in Gmail, Outlook, Yahoo, and Apple Mail. It also covers how to block an IP address at the server level for administrators who need stronger protection.

Why Block an Email Address or IP?

Not every unwanted email is spam. Sometimes it is a former business contact, an ex-colleague, or a newsletter you never signed up for. Other times it is outright malicious: phishing attempts, scam emails, or automated spam from botnets.

Here are the most common reasons to block email:

  • Stop spam from reaching your inbox entirely
  • Block spammers who keep creating new messages to get around filters
  • Prevent phishing by cutting off known bad senders
  • Reduce noise so you only see email that matters
  • Protect your network by blocking malicious IP addresses at the server level

Blocking at the individual level removes a sender from your inbox. Blocking at the IP level stops traffic from an entire server. Both have their place.

How to Block an Email Address in Gmail

Gmail makes it straightforward to block email from specific senders. Here is how to blacklist an email address in Gmail.

1

Open the email from the sender you want to block

Find a message from the unwanted sender in your inbox, spam folder, or any label.

2

Click the three-dot menu

In the top-right corner of the email (next to the reply arrow), click the three vertical dots.

3

Select "Block [sender name]"

Gmail will show the sender's name or email address. Click the block option. A confirmation dialog appears.

4

Confirm the block

Click "Block" in the dialog. Future messages from this sender go straight to spam.

Create a filter for more control

If you want to auto-delete messages instead of sending them to spam, go to Settings > Filters and Blocked Addresses > Create a new filter. Enter the sender's address in the "From" field and choose "Delete it" as the action.

To unblock someone later, go to Settings > See all settings > Filters and Blocked Addresses. Find the blocked address and click "Unblock."

How to Block an Email Address in Outlook and Microsoft 365

Outlook offers blocking on both the desktop client and the web app. The steps differ slightly.

Outlook on the Web (outlook.com / Microsoft 365)

1

Open a message from the sender

Navigate to the email you want to block.

2

Click the three-dot menu in the message toolbar

Look for the overflow menu at the top of the message pane.

3

Select "Block" or "Block sender"

Outlook will block the sender and move existing messages to your Junk folder.

Outlook Desktop (Windows)

1

Right-click the message in your inbox

Find the offending email in your message list.

2

Go to Junk > Block Sender

This adds the sender to your blocked senders list immediately.

You can manage your blocked senders list in Settings > Mail > Junk email. Administrators on Microsoft 365 can also block entire domains from the Exchange admin center using mail flow rules.

How to Block an Email Address in Yahoo Mail

Yahoo Mail supports blocking up to 500 addresses.

1

Open the email from the sender

Find a message from the address you want to block.

2

Click the three-dot menu

It sits in the top toolbar above the message.

3

Select "Block senders"

Yahoo will block the address and give you the option to delete all existing messages from that sender.

To manage blocked addresses, go to Settings > More Settings > Security and Privacy > Blocked addresses.

How to Block an Email Address in Apple Mail

Apple Mail handles blocking at the macOS and iOS level.

macOS

1

Open the message from the unwanted sender

Select the email in your inbox.

2

Click the sender's name in the header

A dropdown appears with the sender's details.

3

Select "Block Contact"

Apple Mail marks future messages from this sender and moves them out of your inbox (behavior depends on your settings in Preferences > Junk Mail).

iPhone / iPad

Open the email, tap the sender's name, tap it again to see the contact card, then tap Block this Contact. The block syncs across all Apple devices signed into the same Apple ID.

Dealing with deliverability issues on your end?

If your own emails are getting blocked, check your domain and IP reputation across major blacklists.

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Server-Level IP Blocking for Administrators

Individual email blocking handles one sender at a time. Server-level IP blocking stops all traffic from an entire IP address or range. This is what administrators use to block spammers at scale.

Firewall Rules

The most direct way to block an IP address. Add a deny rule for the offending IP in your firewall configuration. This stops all connections from that IP, not just email.

Mail Server Configuration

Most mail servers let you block IP addresses directly:

  • Postfix: Add the IP to smtpd_client_restrictions using reject_rbl_client or a manual access map
  • Exchange Server: Use connection filtering in the Edge Transport role to block specific IPs
  • cPanel/WHM: Use the "SMTP Restrictions" or "IP Deny Manager" tools

DNS-Based Blocklists (DNSBLs)

Instead of maintaining your own block list, configure your mail server to query public blacklists like Spamhaus, Barracuda, or SpamCop. These lists are maintained by security organizations and updated constantly. If a sending IP appears on the list, your server rejects the connection automatically.

Be careful with IP blocking

Blocking an IP address can have unintended consequences. Shared hosting means multiple legitimate senders may use the same IP. Always verify the IP is the actual source of abuse before blocking it.

Reporting Spammers vs. Just Blocking Them

Blocking removes a sender from your view. Reporting goes further: it tells your email provider this sender is bad, which helps protect other users.

When to just block:

  • Unwanted but non-malicious senders (newsletters, sales emails)
  • Personal contacts you no longer want to hear from
  • One-off annoyances

When to report as spam:

  • Phishing attempts or scam emails
  • Unsolicited bulk email you never opted into
  • Messages with malicious links or attachments
  • Senders impersonating legitimate companies

Most email providers use spam reports to train their filters. Reporting helps block spammers for everyone, not just you.

When Blocking Is Not Enough

Blocking works for individual senders. But what about persistent spam from constantly changing addresses? Or attacks targeting your mail server from rotating IPs?

This is where blacklisting at the server level matters. Individual blocks are reactive. Blacklist monitoring is proactive.

If you are an email administrator, you should:

  • Subscribe to DNS-based blocklists so your server automatically rejects known bad IPs
  • Monitor your own IP and domain to make sure you are not on a blacklist yourself
  • Set up rate limiting to throttle connections from any single IP
  • Implement email authentication (SPF, DKIM, DMARC) to reject spoofed messages

If you are a regular user and blocking individual senders is not keeping up with the volume, talk to your IT team. The problem likely needs a server-level solution.

Monitor Your Blacklist Status

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