If you're the sender's email admin, make sure the SPF records for your domain at your domain registrar are set up correctly. You add an SPF TXT record that lists the Office 365 messaging servers as legitimate mail servers for your domain. SPF is added as a TXT record that is used by DNS to identify which mail servers can send mail on behalf of your custom domain. This type of configuration can lead us to many false-positive events, in which E-mail message that sent from our customer or business partner can be identified as spam mail. The presence of filtered messages in quarantine. The E-mail message is a spoofed E-mail message that poses a risk of attacking our organization users. ip4 indicates that you're using IP version 4 addresses. (Yahoo, AOL, Netscape), and now even Apple. If you're using IPv6 IP addresses, replace ip4 with ip6 in the examples in this article. You will also need to watch out for the condition where you SPF record contains more than 10 DNS lookups, and take action to fix it when it happens. More info about Internet Explorer and Microsoft Edge, Microsoft Defender for Office 365 plan 1 and plan 2, You don't know all sources for your email, Advanced Spam Filter (ASF) settings in EOP. You need some information to make the record. When this setting is enabled, any message that hard fails a conditional Sender ID check is marked as spam. By looking at your SPF TXT record and following the chain of include statements and redirects, you can determine how many DNS lookups the record requires. Use the step-by-step instructions for updating SPF (TXT) records for your domain registrar. Below is an example of adding the office 365 SPF along with onprem in your public DNS server. Also, if you're using DMARC with p=quarantine or p=reject, then you can use ~all. Step 2: Set up SPF for your domain. Enabling one or more of the ASF settings is an aggressive approach to spam filtering. Your email address will not be published. Fix Your SPF Errors Now SPF Check Path The path for the check is as follows Exchange Admin Center > Protection > Spam Filter > Double Click Default > Advanced Options > Set SPF record: Hard fail: Off One of the prime reasons why Office 365 produces a validation error is an invalid SPF record. Although SPF is designed to help prevent spoofing, but there are spoofing techniques that SPF can't protect against. A typical SPF TXT record for Microsoft 365 has the following syntax: v=spf1 is required. v=spf1 ip4:10.10.10.1/16 mx ptr:Sender.domain.com include:spf.protection.outlook.com ~all. This type of mail threat appears in two flavors: In this section, I would like to review a couple of popular misconceptions that relate to the SPF standard. This is no longer required. As mentioned, in an Exchange-based environment, we can use the Exchange rule as a tool that will help us to capture the event of SPF = Fail and also, choose the required response to such an event. Each SPF TXT record contains three parts: the declaration that it's an SPF TXT record, the IP addresses that are allowed to send mail from your domain and the external domains that can send on your domain's behalf, and an enforcement rule. Best practices and the latest news on Microsoft FastTrack, The employee experience platform to help people thrive at work, Expand your Azure partner-to-partner network, Bringing IT Pros together through In-Person & Virtual events. The simple truth is that we cannot prevent this scenario because we will never be able to have control over the external mail infrastructure that is used by these hostile elements. You can also subscribe without commenting. Messages sent from Microsoft 365 to a recipient within Microsoft 365 will always pass SPF. You then define a different SPF TXT record for the subdomain that includes the bulk email. In order to protect against these, once you have set up SPF, you should also configure DKIM and DMARC for Microsoft 365. If you have anti-spoofing enabled and the SPF record: hard fail (MarkAsSpamSpfRecordHardFail) turned on, you will probably get more false positives. If an email message causes more than 10 DNS lookups before it's delivered, the receiving mail server will respond with a permanent error, also called a permerror, and cause the message to fail the SPF check. Microsoft maintains a dynamic but non-editable list of words that are associated with potentially offensive messages. Default value - '0'. SPF enables receiving mail servers to authenticate whether an email message was sent from an authorized mail server - but only when the domain owner's SPF record is valid. To avoid this, you can create separate records for each subdomain. Messages that use JavaScript or Visual Basic Script Edition in HTML are marked as high confidence spam. I always try to make my reviews, articles and how-to's, unbiased, complete and based on my own expierence. As you can see in the screenshot below, Microsoft has already detected an existing SPF record, marking it invalid.We can safely add include:spf.protection.outlook.com to our SPF record.In your DNS Hosting Provider, look up the SPF record, and click edit. Add include:spf.protection.outlook.com before the -all elementSo in this case it would be:v=spf1 ip4:213.14.15.20 include:servers.mcsv.net include:spf.protection.outlook.com -all. A5: The information is stored in the E-mail header. In reality, we can never be sure in 100%, that the E-mail message is indeed spoofed E-mail message or, a legitimate E-mail message. Figure out what enforcement rule you want to use for your SPF TXT record. Messages that hard fail a conditional Sender ID check are marked as spam. No. If you know all of the authorized IP addresses for your domain, list them in the SPF TXT record, and use the -all (hard fail) qualifier. Phishing emails Fail SPF but Arrive in Inbox Posted by enyr0py 2019-04-23T19:01:42Z. Scenario 1 the sender uses an E-mail address that includes a domain name of a well-known organization. Some services have other, more strict checks, but few go as far as EOP to block unauthenticated email and treat them as spoofed messages. For example, if you are hosted entirely in Office 365 Germany, that is, you have no on-premises mail servers, your SPF TXT record would include rows 1, 4, and 7 and would look like this: If you're already deployed in Office 365 and have set up your SPF TXT records for your custom domain, and you're migrating to Office 365 Germany, you need to update your SPF TXT record. In case you wonder why I use the term high chance instead of definite chance is because, in reality, there is never 100% certainty scenario. You do not need to make any changes immediately, but if you receive the "too many lookups" error, modify your SPF TXT record as described in Set up SPF in Microsoft 365 to help prevent spoofing. In Office 365 based environment (Exchange Online and EOP) beside the option of using Exchange rule, we can use an additional option the spam filter policy. To be able to avoid from a false-positive event, meaning an event in which a legitimate E-mail message mistakenly identified as Spoof mail, I prefer more refinement actions such as send the E-mail to approval, send the E-mail to quarantine and so on. The SPF Record is structured in such a way that you can easily add or remove mail systems to or from the record. Also, if you're only using SPF, that is, you aren't using DMARC or DKIM, you should use the -all qualifier. Misconception 1: Using SPF will protect our organization from every scenario in which hostile element abuses our organizational identity. In the current article series, our primary focus will be how to implement an SPF policy for incoming mail, by using the option of Exchange rule, and not by using the Exchange Online spam filter policy option. Received-SPF: Fail (protection.outlook.com: domain of mydomain.com does not designate 67.220.184.98 as permitted sender) receiver=protection.outlook.com; why spffailed mails normally received? Authentication-Results: spf=none (sender IP is 118.69.226.171) smtp.mailfrom=kien.ngan; thakrale5.onmicrosoft.com; dkim=none (message not signed) header.d=none;thakrale5.onmicrosoft.com; dmarc=none action=none header.from=thakrale5.onmicrosoft.com; Received-SPF: None (protection.outlook.com: kien.ngan does not designate permitted sender hosts) Summary: This article describes how Microsoft 365 uses the Sender Policy Framework (SPF) TXT record in DNS to ensure that destination email systems trust messages sent from your custom domain. One option that is relevant for our subject is the option named SPF record: hard fail. This record works for just about everyone, regardless of whether your Microsoft datacenter is located in the United States, or in Europe (including Germany), or in another location. What is SPF? . When it finds an SPF record, it scans the list of authorized addresses for the record. However, because anti-spoofing is based upon the From address in combination with the MAIL FROM or DKIM-signing domain (or other signals), it's not enough to prevent SRS forwarded email from being marked as spoofed. Mark the message with 'hard fail' in the message envelope and then follow the receiving server's configured spam policy for this type of message. You can list multiple outbound mail servers. In scenario 1, in which the sender uses the identity of a well-known organization, we can never be sure definitively that the E-mail message is indeed a spoofed E-mail. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. For detailed information about other syntax options, see SPF TXT record syntax for Office 365. Join the movement and receive our weekly Tech related newsletter. For more information, see Example: SPF TXT record for multiple outbound on-premises mail servers and Microsoft 365. domain name is the domain you want to add as a legitimate sender. Domain names to use for all third-party domains that you need to include in your SPF TXT record. Read Troubleshooting: Best practices for SPF in Office 365. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. This list is known as the SPF record. Instead, the E-mail message will be forwarded to a designated authority, such as IT person, that will get the suspicious E-mail, and this person will need to carefully examine the E-mail and decide if the E-mail is indeed spoofed E-mail or a legitimate E-mail message that mistakenly identified as Spoof mail. For information about the domains you'll need to include for Microsoft 365, see External DNS records required for SPF. So only the listed mail servers are allowed to send mail, A domain name that is allowed to send mail on behalf of your domain, Ip address that is allowed sending mail on behalf of your domain, ip4:21.22.23.24 or complete range: ip4:20.30.40.0/19, Indicates what to do with mail that fails, Sending mail for on-premise systems public IP Address 213.14.15.20, Sending mail from MailChimp (newsletters service). The SPF TXT record for Office 365 will be made in external DNS for any custom domains or subdomains. The following Mark as spam ASF settings set the SCL of detected messages to 9, which corresponds to a High confidence spam filter verdict and the corresponding action in anti-spam policies. The reason for the outcome of SPF = Fail is related to a missing configuration on the sending mail infrastructure., The E-mail address of the sender, uses the domain name of, The result from the SPF sender verification test is , The popular organization users who are being attacked, The various types of Spoofing or Phishing attacks, The E-mail address of the sender includes our domain name (in our specific scenario; the domain name is, The result of the SPF sender verification check is fail (SPF = Fail).