Ty Anderson

Outlook Junk Mail Filter

Few things in life are as enjoyable as good a aphorism. While thinking through today’s topic, I was browsing the Interweb and stumbled across this great list of aphorisms from the wise sage known as Eeyore. The title of the article employs the word “witticism” instead of aphorism. I like this. I like words (preferably written). Thus, I have a few aphorisms of my own (borrowed or otherwise):

  • Haters gonna hate
  • Spammers gonna Spam
  • Writers gonna write

I can’t do much about this first one but I can tackle the next two in one fell swoop. Today, I will explain the Outlook Junk Mail Filter and provide some helpful hints to tweak its performance.

What is the Outlook Junk Filter?

Managing spam

This is a great question because, most likely you are not receiving large amounts of spam on a daily basis. This is thanks to the fact that most organizations install their spam filters or utilize online services to handle it. And if you are using a free email provider like Outlook.com or a paid service like Office 365, these services actively combat spam before it hits your inbox. They can’t filter all of it however.

This fact is why Outlook has a junk filter. Eventually, junk mail will hit your inbox and you will want to do something about. The Outlook Junk Mail Filter (“JMF”) is an out-of-the-box tool that:

  • resides on the Home > Delete area of the ribbon
  • attempts to protect you from spam/junk mail
  • allows you to customize its behavior

Notice I said the junk filter “attempts” to protect. I think it does a good job but it isn’t perfect. It needs you to teach it your preferences.

Preventing junk mail

By default, the Outlook junk mail filter is active but it is fairly passive because it employs the No Automatic Filtering option. I believe Microsoft uses this initial setting because they want to put you in control. So, initially you can be bombarded with junk mail and adjust your settings to suit your needs. This is better than using a stricter filter from the get-go, never informing the user of the numerous cat-related emails forwarded from their mother (at least in my opinion).

Here is brief explanation of each junk mail filter option:

  • No Automatic Filtering: Very permissive. You will see all items the JMF considers to be spam. That is, unless that sender is already in your blocked senders list.
  • Low: Only “obvious” junk mail will be filtered. The rules for obvious are based upon the:
    • Time sent (or date stamp)
    • Content of message
  • High: With this sitting, the JMF takes serious control and moves almost all junk mail to the junk folder. No filter is fool proof thus, Microsoft is unwilling to say it will catch all junk mail.
  • Safe: This option enables white filtering. Only the emails listed in your safe list will safely make it to your inbox. All others will be rejected by the Junk Mail Filter and placed in the junk mail folder. This might be a good option for your kids’ email accounts. I don’t think it useful in a business context. But what do I know?

No matter which option you choose, you can skip the junk mail folder and send all junk mail to the deleted folder. You accomplish this streamlined strategy by enabling the Permanently delete suspected junk e-mail instead of moving it to the Junk E-mail folder. Wow. That’s a wordy yet accurate description.

If you choose the Low, High, or Safe option, two additional options become active:

  • Disable links and other functionality in phishing messages (recommended)
  • Warn me about suspicious domain names in e-mail addresses (recommended)

If you opt for any of these three options, it is worth enabling these options as well.

What are the minimum requirements?

The Junk Mail Filter was born with the release of Outlook 2003. It has been included with each subsequent Outlook release. Thus, JMF lives in Outlook 2003-1013. But, the Junk Mail Filter does not support every email account type. You need any of the following email types:

  • Exchange accounts in Cached Exchange Mode
  • Exchange account that delivers to an Outlook Data File (.pst)
  • POP3 account
  • IMAP account
  • Outlook Connector for Outlook.com (formerly Hotmail)
  • Microsoft Outlook Connector for IBM Lotus Domino

Best practices for junk mail management

Best practices are not necessarily an accurate label. Typically, a best practices list is an experienced person’s description of strategies they find effective.
With this statement in mind, I present my list of Junk Mail Filter best practices.

Best practices for junk mail management

  • Turn the damn thing on!
  • Check your junk mail folder regularly. You decide what regularly means. At a minimum, you should check it weekly. And if you Mom sent you a cat-related email, do the right thing and respond…tell how cute it is.
  • Fiddle with the settings (i.e. safe lists, blocked lists, etc.) and make the Junk Mail Filter work for you. If you like all those emails from Amazon.com trying to entice you to buy stuff you don’t need, fine, put them in the safe list. If not, block them.
    • Look through your blocked senders list. Look for senders that have be incorrectly blocked. Remove them and add them to the safe senders list.
    • Do the same with the safe senders list but look for senders you want to block. Remove them and add them to the blocked senders list.
  • Check for updates to the junk e-mail definition files. Microsoft publishes them as they have them. You can typically find them here.
  • Remind yourself that spammers don’t typically reuse email addresses. Thus, don’t spend your time trying to add every spammer to your blocked senders list. You can add it but the spammer most likely will not use that email address again.
  • Ask yourself, “Is this level of protection working for me? Do I like the job the Junk Mail Filter is doing for me?”
    • If you answer in the affirmative, you’re done.
    • If you answer in the negative, increase or decrease the filter setting. Give a week and re-assess.

Other Items you should consider (but I believe are not needed):

I leave my Junk Mail Filter on the lowest setting. Thus some filter options are not available to me. I leave it like this because I follow my trusty email rules. But, if you want extra bits of security, do the following:

  • Enable the option that hides phishing links and related functionality.
  • Enable the option that warns you about suspicious domains.

Outlook tool for filtering junk mail

If you are looking for additional tools that allow for further tweaking of the junk mail, take a look at these tools. I made this list of my own free will. I am not a paid endorser. In fact, I’m not even endorsing them. They are simply tools that work with Outlook and filter spam.

Junk mail and custom solutions

Before I end this topic, let’s briefly discuss how developers can work with junk mail items in Outlook. If writing an Outlook add-in:

  • The junk mail folder is an Outlook folder. Working with the junk mail folder is the same as working with any other Outlook. The objects are the same. The events are the same. In fact, it is a default folder and can be accessed with a call to Session.GetDefaultFolder(olFolderJunk).
  • If you are working with MailItems, be sure and regularly scan the contents of the junk mail folder. The reason why will vary based on your business rules. But if you are looking in the inbox for certain email items and they are not there, there is a chance the junk mail filter placed them in the junk mail folder.
  • There is no reason why you can’t utilize the junk mail filter in your add-in. You can create logic to implements your own junk mail rules and place the identified mail items in the junk folder.

If your Outlook add-in auto-generates and sends emails within Outlook, you will want to avoid having your email filtered by your recipient’s Outlook junk mail filter. I wish I could give you a definitive guide for avoiding it.

If this guide existed, well, the spammers would use it and it wouldn’t be much of a guide. The best I can tell just follow these guidelines:

  • Don’t create emails that look like spam.
    • Use proper grammar
    • The email needs to contain real and relevant (to the recipient) content
  • Don’t send a bunch of emails late at night. Send them during normal business hours.
  • Watch your formatting. Don’t create emails that look like a robot wrote them.
  • Send from a valid domain name.
  • Send from a valid domain name.

Basically, be a good citizen of the Internet and build tools that help the user do their job within Outlook. Of course, you can do everything correctly and still have the user manually add you to their blocked senders list. In this case, there is nothing you can do about it.


For me, the Junk Mail Filter (plus the filter Office 365 provides) does the trick. I check my junk mail folder 2-3 times per month and find only a handful of items. All of the items turn out to be junk 90% of the time. Definitely, I think you should tweak your settings and find what works best for you. By doing so, you can spend less time messing with junk mail and focus on other things.

Thing like:
Developers gonna develop!

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