Setting Outlook spam filter to stop junk email

How Outlook spam filter works

Before delving into setting up the Outlook Junk Mail filter, it's important to have a basic understanding of how it works. Here are some key points to keep in mind:

• Outlook comes with a built-in spam filter that automatically identifies and moves suspicious emails to the Junk folder, but it doesn't entirely block junk emails from reaching your Outlook.
• The filter supports various email account types, including Exchange Server accounts, POP3, IMAP, HTTP, Outlook Connector for Outlook.com and IBM Lotus Domino.
• By default, the Outlook spam filter is set to No Automatic Filtering. However, you can adjust the level of protection for more aggressive filtering.
• Typically, the Junk Mail filter runs before Outlook email rules come into play. If you're using an Exchange server, remember that its server-side spam filter always has priority. Consequently, any rules you set up won't apply to messages that have been moved to the spam folder already.
• In newer versions (Outlook 2010 - 365), the spam filter settings are applied to each email account individually. If you have multiple accounts, the Junk Email options dialog will display settings for the account whose folders you're currently viewing.
• Finally, it's important to note that while the Outlook Junk Email Filter provides significant protection against spam, no filter is foolproof in identifying every unsolicited email, even when set to the highest level. The filter does not pick out any particular sender or a message type. It analyzes each incoming message, taking into account factors like message structure, content, and timing to determine the likelihood of spam.

Outlook spam folder

The Spam folder in Outlook, also known as the Junk folder, is a repository where suspected spam emails are automatically diverted by Outlook's filtering mechanisms. These mechanisms analyze incoming emails based on various criteria such as sender reputation, content, and user behavior to determine whether they are likely to be spam.

Where is the spam folder in Outlook?

The spam folder is typically located in the folder pane on the left side of the Outlook window. Its name may vary slightly depending on the version of Outlook you are using. In the current versions of Outlook 365, the new Outlook, and web app, it is named Junk Email.  If you can't see it, you might need to scroll down or expand the folder list.

How to configure Outlook junk mail settings to automatically filter spam

The Outlook Junk Email Filter automatically scans your incoming emails, but you can adjust its settings to provide the filter with guidance on what to identify as spam. In the below instructions, we'll use Outlook 365, but the settings are essentially the same in all versions of Outlook 2010 - 2021, so you won't have any problems with following.

To enable the Outlook spam filter, carry out these steps:

1. Access Outlook junk mail settings
2. Choose spam protection level
3. Prevent good e-mails from being classified as junk
4. Block malicious senders
5. Block top-level domains and encodings

By clicking on the links above, you'll be taken to the section that has all the juicy details about each step.

Set junk email protection level

On the Options tab, you choose the desired level of spam protection:

• No Automatic Filtering - no automatic junk mail filtering, but emails from the Blocked Senders list are still moved to the Junk folder.
• Low - the most tolerant option that filters only the most obvious spam.
• High - catches most spam emails but may also misidentify legitimate messages and move them to the spam folder. If you choose this option, don't forget to periodically review your Junk mail folder.
• Safe lists only - the maximum level of protection that only allows emails from people in the Safe Senders and Safe Recipients lists.

Besides the protection levels, two more options are available to you:

• Permanently delete suspected spam email instead of moving it to Junk folder
• Warn about suspicious domain names in e-mail addresses (available for any protection level other than No Automatic Filtering)

Tips and notes:

• It is recommended to test which option works best for you over a short period. If too much spam is still getting into your inbox, switch to the High setting. On the other hand, if too many legitimate emails such as subscribed newsletters are being mistakenly filtered as spam, switch to the Low setting.
• The Safe Lists Only option may not be the best choice as it requires manually adding safe senders to a list. Any sender not on the list will be filtered as spam, which can include legitimate emails from new clients or customers requesting quotes.
• Enabling the Permanently delete suspected junk email option leaves no chance to recover a message mistakenly treated as junk. It's advisable to periodically check the spam folder instead of relying on this option.

Block malicious senders

On the Blocked Senders tab, you can see email addresses that are already blocked, add more senders to the list or unblock a particular sender. All messages from blocked senders are considered spam and automatically moved to the Junk folder.

To block a sender, click the Add button, and then type an e-mail address or domain name in the pop-up dialog box.

To remove someone from junk, select it in the Blocked Senders list and click the Remove button.

Tip. Another quick way to block a specific spammer is to right-click the message and choose Junk > Block Sender from the context menu. To remove a good contact from junk, choose Never Block Sender.

For more information, please see How to block a sender in Outlook.

Junk mail settings in Outlook 365 online

If you are using Outlook 365 as a web application (Outlook Online), then you can change junk mail settings by following these steps:

1. Sign in to Outlook on the web.
2. At the top of the screen, click Settings (the gear icon), then View all Outlook settings.
3. In the window that opens, select Mail > Junk email.
4. Add addresses to the Safe Senders and Domains or Blocked Senders and Domains lists. Change Filters and Reporting as desired.

Why Blocked Senders list is not the best way to stop junk email

While it may seem that adding unwanted senders to the Blocked list is the easiest solution to prevent spam, this method is not very effective for several reasons:

• Spammers rarely use the same email address more than once, so adding individual addresses to the Blocked list is a futile effort.
• For Microsoft Exchange Server accounts, there is a limit of 1024 addresses for the Blocked Senders list and two Safe lists combined.
• When receiving email, the first thing that Outlook does is check it against the junk filter lists. So, the longer your lists, the slower Outlook will process incoming messages.

Considering the above, the most effective approach is to keep your spam filter lists as short as possible.

However, if you are inundated with an overwhelming number of unwanted emails, you may wonder what you should do. In case numerous spam messages are sent from a particular domain, it makes sense to add it to your Blocked Senders list. To block the entire domain, there is no need to enter sub-domains or use wild characters. You can ban the whole domain by simply entering @spam-domain.com, and this will stop all junk mail coming from that domain.

How to keep Outlook Junk Email Filter up to date

Although most spam is easily identifiable, some spammers carefully study Microsoft's spam filter technology to improve their strategies. On the other hand, Microsoft works hard to combat spam and regularly updates their filter to reduce junk email. Therefore, it is advisable to update Outlook regularly to ensure the latest version of the filter is installed.

To enable automatic updates in Outlook, follow these steps:

1. Start Outlook.
2. On the File tab, select Office Account.
3. On the right side, click Update Options > Enable Updates.

How to report spam to Microsoft

Even if you have the latest version of the Outlook spam filter, some spam emails may still end up in your inbox. You can assist Microsoft in enhancing the efficiency of their junk email filtering technologies by reporting such messages to them.

Currently, the inbuilt Report button is only available in Outlook on the web (OWA). To report spam to Microsoft, here's what you do:

1. In Outlook on the web, select one or more unsolicited emails.
2. On the top menu, click Report, and then select either Report phishing or Report junk.

In desktop Outlook, there is no built-in Report button. As an alternative, you can use free Microsoft Report Message and Report Phishing add-ins. Or you can submit a report through the Microsoft 365 Defender portal.

How to mark an email as not junk in Outlook

Legitimate emails can sometimes be mistaken as spam and moved to the Junk folder. It is important to remember to check this folder occasionally, as no filter is perfect. If you set your Outlook spam filter to the High level to prevent as much junk mail as possible, it is recommended to check your spam folder frequently. Checking it at the end of your workday is a good practice to ensure that you have covered everything.

If a legitimate message appears among junk emails, you can mark it as not junk in this way:

1. Right click the message, and then click Not Junk.
2. From the context menu, choose one of the options: Never Block Sender, Never Block Sender's Domain or Not Junk.

Clicking Never Block Sender or Never Block Sender's Domain will add the sender's address or domain name to your Safe Senders list, so the Outlook spam filter won't make the same mistake again.

Choosing Not Junk will move the message from the Junk folder to your Inbox. Additionally, you can select the Always trust e-mail from… option to add that email address to the Safe Senders list.

If you do not wish to add a specific sender to your safe list, you can simply drag a misidentified junk message to any other folder using the mouse.

How to turn off Junk Mail Filter in Outlook

To turn off Outlook's junk mail filter, this is what you need to do:

1. In your Outlook, open the Junk E-mail Options dialog box (Home tab > Junk> Junk E-mail Options).
2. On the Options tab, select No Automatic Filtering. This will stop automatic mail filtering, but messages from the Blocked Senders list will still be moved to the spam folder.
3. Review the Blocked Senders list and clear it if needed. To have it done, switch to the Blocked Senders tab, select the addresses/domains and click the Remove button.