Reporting spam/ phishing email addresses

Question

Reporting spam/ phishing email addresses

Sam P 20

Greetings,

Instead of blocking the emails through their address. Why not block them via their domains *.domain.com. For most this would block a majority of the same emails where they just change the user name. Getting tired of receiving emails from onmicrosoft.com, firebaseapps.com, etc, etc..

0 comments

Answer accepted by question author

Winnie-B 9,930 Microsoft External Staff Moderator

Hi Sam P

Thank you for reaching out to Microsoft Q&A Forum. Your suggestion is spot on, blocking by domain is often more effective than blocking one address at a time, especially when spammers keep changing the username portion of the sender address.

Please try the following steps:

1. Block the domain in Outlook web

Please do this in Outlook on the web:

Sign in to Outlook on the web
Select Settings> Mail > Junk email
Under Blocked senders and domains, select Add
Enter the domain and Save

2. Add an Inbox rule to automatically move/delete future spam

If the spam keeps coming from variations of the same domain, an Inbox rule can reduce the manual work by moving or deleting those messages automatically

Still in Outlook on the web, select Settings > Mail > Rules > Add new rule
Set up the rule with one of these common options (pick the one that matches what you see):
- Condition: Sender address includes > enter the domain you want to catch
- Action: Move to > Junk Email or Delete (your preference)
Select Stop processing more rules > Save

You can also see Manage email messages by using rules in Outlook - Microsoft Support

3. Report as phishing (optional)

Right‑click the email > Report > Phishing
This helps Outlook improve filtering for similar spam

If you still receive spam from a specific domain even after trying the above steps, please feel free to let me know so I can assist you further. Thank you for your understanding.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Sam P 20 Reputation points

2026-01-21T23:32:21.2233333+00:00

I've added the root @domain.com as suggested but I'm still receiving email from the same domains. i.e. firebaseapps.com, onmicrosoft.com, longlifehappylife,.com are a few. If there a limit to what can be added to the blocked domains?

Thank you for your time
Winnie-B 9,930 Reputation points Microsoft External Staff Moderator

2026-01-22T01:50:09.7366667+00:00
Good day Sam P

Thanks for the update, and I’m sorry those messages are still getting through. Please check these:

1. First, make sure the domain is added in the correct format (Outlook on the web)

Still in Outlook on the web, go to Settings> Mail > Junk email

Under Blocked senders and domains, enter the domain without @ or *, please add it as domain.com, and not @domain.com

2. And just to confirm, have you tried adding that Inbox rule yet? (step 2 above)

Because spammers rotate addresses constantly, Microsoft also recommends using an Inbox rule when blocking alone doesn’t stop the flow.

3. Check whether the “From” domain is spoofed

Since you’re still getting mail that looks like it’s from the same domains even after blocking them, the most likely reason is spoofing (the “From” domain shown can be faked). In that case, Outlook may still receive the message using a different identity, so blocking what you see (like domain.com) won’t reliably stop all of them.

Please open one of the unwanted emails in Outlook and view its headers, Microsoft shows how to do this here: View internet message headers in Outlook - Microsoft Support

Once you identify the actual domain/email from the headers, block that exact domain in Outlook on the web:

Go to Settings > Mail > Junk email

Under Blocked senders and domains, add the exact email address or domain you found in the headers, then Save.

After you identify the real sender/domain, you can also add an Inbox rule in Outlook on the web to automatically delete or move those messages (instead of leaving them in Junk).

I truly hope this helps! Thank you again for your understanding and cooperation.

1 additional answer

Your answer

Sam P 20 Reputation points

2026-01-21T23:32:21.2233333+00:00

I've added the root @domain.com as suggested but I'm still receiving email from the same domains. i.e. firebaseapps.com, onmicrosoft.com, longlifehappylife,.com are a few. If there a limit to what can be added to the blocked domains?

Thank you for your time
Winnie-B 9,930 Reputation points Microsoft External Staff Moderator

2026-01-22T01:50:09.7366667+00:00

Good day Sam P

Thanks for the update, and I’m sorry those messages are still getting through. Please check these:

1. First, make sure the domain is added in the correct format (Outlook on the web)

Still in Outlook on the web, go to Settings> Mail > Junk email

Under Blocked senders and domains, enter the domain without @ or *, please add it as domain.com, and not @domain.com

2. And just to confirm, have you tried adding that Inbox rule yet? (step 2 above)

Because spammers rotate addresses constantly, Microsoft also recommends using an Inbox rule when blocking alone doesn’t stop the flow.

3. Check whether the “From” domain is spoofed

Since you’re still getting mail that looks like it’s from the same domains even after blocking them, the most likely reason is spoofing (the “From” domain shown can be faked). In that case, Outlook may still receive the message using a different identity, so blocking what you see (like domain.com) won’t reliably stop all of them.

Please open one of the unwanted emails in Outlook and view its headers, Microsoft shows how to do this here: View internet message headers in Outlook - Microsoft Support

Once you identify the actual domain/email from the headers, block that exact domain in Outlook on the web:

Go to Settings > Mail > Junk email

Under Blocked senders and domains, add the exact email address or domain you found in the headers, then Save.

After you identify the real sender/domain, you can also add an Inbox rule in Outlook on the web to automatically delete or move those messages (instead of leaving them in Junk).

I truly hope this helps! Thank you again for your understanding and cooperation.

Answer 1

Blocking emails by their domains (e.g., *.domain.com) can indeed help reduce the number of unwanted emails, especially if the sender frequently changes usernames. However, it's important to note that while this method may block many emails from that domain, it can also inadvertently block legitimate emails from the same domain.

In Microsoft 365, you can manage blocked senders and domains through anti-spam policies. You can add domains to the blocked domains list, which would prevent emails from any address within that domain from reaching your inbox. However, be cautious when adding common domains, as this could lead to missing important communications.

For the best results, consider using a combination of blocking specific email addresses and domains, along with reporting spam and phishing attempts to Microsoft to help improve their filtering systems. This way, you can maintain a balance between blocking unwanted emails and ensuring you still receive legitimate communications.

References: