Send & Receive Issues

How to Fix Cannot Block Sender in MSN or Outlook.com Mail

Adam Davis Sep 29, 2026 869 views

Question details

The user is unable to successfully block a sender in MSN or Outlook.com, either receiving an error message or finding that the blocking action does not seem to work.

How to Fix Cannot Block Sender in MSN or Outlook.com Mail

Product: Outlook.com / MSN Mail
Device & OS: not provided
Scenario: Attempting to block unwanted spam or specific email addresses from reaching the inbox.
Observed behavior: The system prevents adding new addresses to the blocked list, or the user notices that emails from blocked senders are still being delivered to their account.

Before you start

Log in to your Outlook.com or MSN webmail account on a desktop web browser to easily access and manage your complete Junk email settings.

Solution 1Recommended

Free Up Space in the Blocked Senders List

Outlook.com limits the blocked senders list to approximately 1,024 entries. If your list is full, you must remove old entries before adding new ones.

When the blocked senders and domains list reaches its maximum capacity, you will trigger an error when trying to block someone new. Regularly maintaining this list resolves the issue.

Open Settings

Log into Outlook.com and click the gear icon in the top right corner to open your account Settings.

Navigate to Junk Email

Go to 'Mail' in the left sidebar, then select 'Junk email'.

Remove Old Entries

Review the 'Blocked senders and domains' list. Click the trash can icon next to older or unused email addresses to free up space.

Add New Sender

Type the new email address or domain you wish to block in the text box and press 'Add'.

Free Up Space in the Blocked Senders List

List Capacity: Keeping your blocked senders list curated ensures you always have room to block active spam sources.

Solution 2

Verify Outlook's Blocking Behavior

Understand that blocking a sender in Outlook does not completely prevent delivery; it simply routes their emails straight to your Junk folder.

Solution 3

Report Persistent Unwanted Emails

If you cannot block a sender directly, use Microsoft's built-in reporting tools to train the spam filter against the sender.

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Frequently Asked Questions

What is the maximum number of blocked senders allowed in Outlook.com?

Outlook.com allows approximately 1,024 entries in the blocked senders and domains list. Once this limit is reached, you must manually delete older or unnecessary entries before you can add new addresses.

Why am I still receiving emails from a blocked sender?

In MSN and Outlook.com, blocking a sender does not stop their emails from being delivered to your account entirely. Instead, the system automatically intercepts and routes those messages directly to your Junk Email folder.

Can I block an entire domain instead of individual email addresses?

Yes. In the Junk email settings under 'Blocked senders and domains', you can type a domain name (for example, 'example.com') to block all incoming mail originating from that specific domain.

Outlook & Email Problems