With a soft fail, this will get tagged as spam or suspicious. The -all rule is recommended. This setting combines an SPF check with a Sender ID check to help protect against message headers that contain forged senders. The element which needs to be responsible for capturing event in which the SPF sender verification test considered as Fail is our mail server or the mail security gateway that we use. Some bulk mail providers have set up subdomains to use for their customers. In reality, most of the organization will not implement such a strict security policy because they would prefer to avoid a false-positive scenario in which a legitimate mail mistakenly identified as Spoof mail. If you have a hybrid configuration (some mailboxes in the cloud, and some mailboxes on premises) or if you're an Exchange Online Protection standalone customer, add the outbound IP address of . Generate and Send an incident report to a designated recipient (shared mailbox) that will include information about the characters of the event + the original E-mail message. The SPF Record is structured in such a way that you can easily add or remove mail systems to or from the record. Typically, email servers are configured to deliver these messages anyway. For advanced examples and a more detailed discussion about supported SPF syntax, see How SPF works to prevent spoofing and phishing in Office 365. To be able to get a clearer view of the different SPF = Fail scenarios, lets review the two types of SPF = Fail events. Attackers will adapt to use other techniques (for example, compromised accounts or accounts in free email services). Phishing emails Fail SPF but Arrive in Inbox Posted by enyr0py 2019-04-23T19:01:42Z. Although SPF is designed to help prevent spoofing, but there are spoofing techniques that SPF can't protect against. For example: Having trouble with your SPF TXT record? 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. IT, Office365, Smart Home, PowerShell and Blogging Tips. However, over time, senders adjusted to the requirements. Use the step-by-step instructions for updating SPF (TXT) records for your domain registrar. See You don't know all sources for your email. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. If you have a hybrid configuration (some mailboxes in the cloud, and some mailboxes on premises) or if you're an Exchange Online Protection standalone customer, add the outbound IP address of . Suppose a phisher finds a way to spoof contoso.com: Since IP address #12 isn't in contoso.com's SPF TXT record, the message fails the SPF check and the receiver may choose to mark it as spam. Hope this helps. How to enforce SPF fail policy in Office 365 (Exchange Online) based environment, The main two purposes of using SPF mechanism, Scenario 1: Improve our E-mail reputation (domain name), Scenario 2: Incoming mail | Protect our users from Spoof mail attack, The popular misconception relating to SPF standard. Microsoft itself first adopted the new email authentication requirements several weeks before deploying it to customers. If you do not use any external third-party email services and route all your emails via Office 365, your SPF record will have the following syntax: v=spf1 include:spf.protection.outlook.com -all. This option combines an SPF check with a Sender ID check to help protect against message headers that contain forged senders. Learn about who can sign up and trial terms here. Basically, SPF, along with DKIM, DMARC, and other technologies supported by Office 365, help prevent spoofing and phishing. What is SPF? SPF records in Office 365 are DNS records that help authenticate Office 365 based emails so organizations can operate with higher levels of trust and prevent spoofing. For a list of domain names you should include for Microsoft 365, see External DNS records required for SPF. The protection layers in EOP are designed work together and build on top of each other. In case we decide to activate this option, the result is that each of the incoming E-mails accepted by our Office 365 mail server (EOP), and that include SPF sender verification results of SPF = Fail, will automatically be marked as spam mail. Conditional Sender ID filtering: hard fail. Even in a scenario in which the mail infrastructure of the other side support SPF, in case that the SPF verification test marked as Fail, we cannot be sure that the spoofed E-mail will be blocked. Read the article Create DNS records at any DNS hosting provider for Microsoft 365 for detailed information about usage of Sender Policy Framework with your custom domain in Microsoft 365. A7: Technically speaking, each recipient has access to the information that is stored in the E-mail message header and theoretically, we can see the information about the SPF = Fail result. An SPF record is a DNS entry containing the IP addresses of an organization's official email servers and domains that can send emails on behalf of your business. You add an SPF TXT record that lists the Office 365 messaging servers as legitimate mail servers for your domain. What is the recommended reaction to such a scenario? 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. The sender identity can be any identity, such as the sender identity of a well-known organization/company, and in some cases; the hostile element is rude enough to use the identity of our organization for attacking one of our organization users (such as in spear phishing attack). (e.g., domain alignment for SPF); d - send only if DKIM fails; s - send only when SPF fails. What is the conclusion such as scenario, and should we react to such E-mail message? To get started, see Use DKIM to validate outbound email sent from your custom domain in Microsoft 365. In this scenario, our mail server accepts a request to deliver an email message to one of our organization recipients. In this phase, we will need to decide what is the concrete action that will apply for a specific E-mail message that will identify a Spoof mail (SPF = Fail). If you have anti-spoofing enabled and the SPF record: hard fail (MarkAsSpamSpfRecordHardFail) turned on, you will probably get more false positives. In the next article, Implementing SPF Fail policy using Exchange Online rule (dealing with Spoof E-mail attack) | Phase 1 learning mode | Part 2#3, we will review the step-by-step instruction needed to create an Exchange Online rule that will help us to monitor such events. SPF identifies which mail servers are allowed to send mail on your behalf. A5: The information is stored in the E-mail header. We can certainly give some hints based on the header information and such, but it might as well be something at the backend (like the changes which caused the previous "incident"). If you're not sure that you have the complete list of IP addresses, then you should use the ~all (soft fail) qualifier. Based on your mentioned description about "SPF authentication fails for our outbound emails sent by Exchange Online despite having this DNS record : v=spf1 include:spf.protection.outlook.com -all", once could you please provide us your detailed error message screenshot, your SPF record and domain via private message? In many scenarios, the spoofed E-mail message will not be blocked even if the SPF value marked as Fail because of the tendency to avoid a possible event of false positives. In all Microsoft 365 organizations, the Advanced Spam Filter (ASF) settings in anti-spam policies in EOP allow admins to mark messages as spam based on specific message properties. Did you know you can try the features in Microsoft 365 Defender for Office 365 Plan 2 for free? Step 2: Set up SPF for your domain. The meaning of the SPF = Fail is that we cannot trust the mail server that sends the E-mail message on behalf of the sender and for this reason, we cannot trust the sender himself. A wildcard SPF record (*.) is the domain of the third-party email system. When this mechanism is evaluated, any IP address will cause SPF to return a fail result. 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. Enabling one or more of the ASF settings is an aggressive approach to spam filtering. If you set up mail when you set up Microsoft 365, you already created an SPF TXT record that identifies the Microsoft messaging servers as a legitimate source of mail for your domain. For instructions, see Gather the information you need to create Office 365 DNS records. This tag allows plug-ins or applications to run in an HTML window. An SPF record is required for spoofed e-mail prevention and anti-spam control. What happens to the message is determined by the Test mode (TestModeAction) value: The following Increase spam score ASF settings result in an increase in spam score and therefore a higher chance of getting marked as spam with a spam confidence level (SCL) of 5 or 6, which corresponds to a Spam filter verdict and the corresponding action in anti-spam policies. If an SPF TXT record exists, instead of adding a new record, you need to update the existing record. Per Microsoft. Despite my preference for using Exchange rule as preferred tool for enforcing the required SPF policy, I would also like to mention an option that is available for Office 365 customers, which their mail infrastructure based on Exchange Online and EOP (Exchange Online Protection). You can also subscribe without commenting. To do this, change include:spf.protection.outlook.com to include:spf.protection.outlook.de. 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. We are going to start with looking up the DNS records that Microsoft 365 is expecting and then add the correct SPF record to our DNS hosting provider: First, we are going to check the expected SPF record in the Microsoft 365 Admin center. @tsulaI solved the problem by creating two Transport Rules. Specifically, the Mail From field that . To be able to use the SPF option we will need to implement by ourselves the following proceeds: Add to the DNS server that hosts our domain name the required SPF record, and verifies that the syntax of the SPF record is correct + verify that the SPF record includes information about all the entities that send an E-mail message on behalf of our domain name. Its Free. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. The meaning of SPF =none is that a particular organization that is using a specific domain name doesnt support SPF or in other words, doesnt enable us to verify the identity of the sender that their E-mail message includes the specific domain name. The number of messages that were misidentified as spoofed became negligible for most email paths. In order to protect against these, once you have set up SPF, you should also configure DKIM and DMARC for Microsoft 365. The Microsoft 365 Admin Center only verifies if include:spf.protection.outlook.com is included in the SPF record. Include the following domain name: spf.protection.outlook.com. For example, at the time of this writing, Salesforce.com contains 5 include statements in its record: To avoid the error, you can implement a policy where anyone sending bulk email, for example, has to use a subdomain specifically for this purpose. Recipient mail systems refer to the SPF TXT record to determine whether a message from your custom domain comes from an authorized messaging server. Required fields are marked *. 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. Scenario 2. 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. Microsoft believes that the risk of continuing to allow unauthenticated inbound email is higher than the risk of losing legitimate inbound email. SPF sender verification test fail | External sender identity. The Exchange rule includes three main parts: In our specific scenario, we will use the Exchange rule using the following configuration setting-, Phase 1. Learning about the characters of Spoof mail attack. For example: Previously, you had to add a different SPF TXT record to your custom domain if you were using SharePoint Online. Use trusted ARC Senders for legitimate mailflows. Take a look at the basic syntax for an SPF rule: For example, let's say the following SPF rule exists for contoso.com: v=spf1 . Do nothing, that is, don't mark the message envelope. Did you know you can try the features in Microsoft 365 Defender for Office 365 Plan 2 for free? This article was written by our team of experienced IT architects, consultants, and engineers. 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. This option enables us to activate an EOP filter, which will mark incoming E-mail message that has the value of "SFP =Fail" as spam mail (by setting a high SCL value). If you're the sender's email admin, make sure the SPF records for your domain at your domain registrar are set up correctly. For example, if you are hosted entirely in Office 365, that is, you have no on-premises mail servers, your SPF TXT record would include rows 1, 2, and 7 and would look like this: The example above is the most common 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. A3: To improve the ability of our mail infrastructure, to recognize the event in which there is a high chance, that the sender spoofs his identity or a scenario in which we cannot verify the sender identity.The other purpose of the SPF is to protect our domain mane reputation by enabling another organization to verify the identity of an E-mail message that was sent by our legitimate users. For advanced examples, a more detailed discussion about supported SPF syntax, spoofing, troubleshooting, and how Office 365 supports SPF, see How SPF works to prevent spoofing and phishing in Office 365. IP address is the IP address that you want to add to the SPF TXT record. Despite that the first association regarding the right response to an event in which the sender uses an E-mail address that includes our organization domain name + the result from the SPF sender verification test is fail, is to block and delete such E-mails; I strongly recommend not doing so. In reality, the recipient will rarely access data stored in the E-mail message header, and even if they access the data, they dont have the ability to understand most of the information thats contained within the E-mail header. A8: The responsibility of the SPF mechanism is to stamp the E-mail message with the SPF sender verification test results. A good option could be, implementing the required policy in two phases-. For example, suppose the user at woodgrovebank.com has set up a forwarding rule to send all email to an outlook.com account: The message originally passes the SPF check at woodgrovebank.com but it fails the SPF check at outlook.com because IP #25 isn't in contoso.com's SPF TXT record. This tag is used to create website forms. The E-mail message is a spoofed E-mail message that poses a risk of attacking our organization users. The setting is located at Exchange admin Center > protection > spam filter > double click Default > advanced options > set SPF record: hard fail: off . In this phase, we are only capturing event in which the E-mail address of the sender uses the domain name of our organization, and also; the result from the SPF sender verification test is Fail. No. When Microsoft enabled this feature in 2018, some false positives happened (good messages were marked as bad). The main purpose of SPF is to serve as a solution for two main scenarios: A Spoof mail attacks scenario, in which hostile element abuses our organizational identity, by sending a spoofed E-mail message to external recipients, using our organizational identity (our domain name). Enforcement rule is usually one of the following: Indicates hard fail. In this scenario, we can choose from a variety of possible reactions.. SPF, together with DKIM and DMARC helps to prevent spoofing of your mail domain. If the sender isn't permitted to do so, that is, if the email fails the SPF check on the receiving server, the spam policy configured on that server determines what to do with the message. For example, one of the most popular reasons for the result fail when using the SPF sender verification test is a problem or a miss configuration, in which the IP address of one of our mail server/services that our organization use, was not added to the SPF record. In case we want to get more information about the event or in case we need to deliver the E-mail message to the destination recipient, we will have the option. SPF record types were deprecated by the Internet Engineering Task Force (IETF) in 2014. In case that your organization experiences a scenario in which your mail server IP address, In the current article and the next article: My E-mail appears as spam | Troubleshooting, In the current article, we will review how to deal with Spoof mail by creating, Your email address will not be published. The following examples show how SPF works in different situations. An SPF record is used to identify which mail servers (or systems) are allowed to send mail on your behalf. This is the default value, and we recommend that you don't change it. Mark the message with 'soft fail' in the message envelope. In case the mail server IP address that sends the E-mail on behalf of the sender, doesnt appear as authorized IP address in the SPF record, SPF sender verification test result is Fail. Test mode is not available for this setting. Given that the SPF record is configured correctly, and given that the SPF record includes information about all of our organizations mail server entities, there is no reason for a scenario in which a sender E-mail address which includes our domain name will mark by the SPF sender verification test as Fail. It doesn't have the support of Microsoft Outlook and Office 365, though. The following Mark as spam ASF settings set the SCL of detected messages to 6, which corresponds to a Spam filter verdict and the corresponding action in anti-spam policies. Received-SPF: Fail (protection.outlook.com: domain of mydomain.com does notdesignate 67.220.184.98 as permitted sender) receiver=protection.outlook.com; i check SPF at mxtoolbox and SPF is correctly configured. The SPF mechanism doesnt perform and concrete action by himself. This will avoid the rejections taking place by some email servers with strict settings for their SPF checks. Join the movement and receive our weekly Tech related newsletter. This tag allows the embedding of different kinds of documents in an HTML document (for example, sounds, videos, or pictures). For example in Exchange-based environment, we can add an Exchange rule that will identify SPF failed events, and react to this type of event with a particular action such as alert a specially designated recipient or block the E-mail message. You intend to set up DKIM and DMARC (recommended). Domain administrators publish SPF information in TXT records in DNS. 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. Gather this information: The SPF TXT record for your custom domain, if one exists. (Yahoo, AOL, Netscape), and now even Apple. The 6 commonly used elements in an SPF record are: You can add as many include: or ip4: elements to your SPF record as you need. The answer is that as always; we need to avoid being too cautious vs. being too permissive. This type of scenario, there is a high chance that we are experiencing a Spoof mail attack! For more information, see Configure anti-spam policies in EOP. We don't recommend that you use this qualifier in your live deployment. Sender Policy Framework (SPF) allows email administrators to reduce sender-address forgery (spoofing) by specifying which are allowed to send email for a domain. The only thing that we can do is enable other organizations that receive an email message that has our domain name, the ability to verify if the E-mail is a legitimate E-mail message or not. This is the main reason for me writing the current article series. If you provided a sample message header, we might be able to tell you more. If you have a hybrid deployment (that is, you have some mailboxes on-premises and some hosted in Microsoft 365), or if you're an Exchange Online Protection (EOP) standalone customer (that is, your organization uses EOP to protect your on-premises mailboxes), you should add the outbound IP address for each of your on-premises edge mail servers to the SPF TXT record in DNS. Secondly, if your user has the sender's address added to their safe senders list, or sender address is in contacts + contacts are trusted, the message would skip spam filtering and be delivered to inbox. This defines the TXT record as an SPF TXT record. From my experience, the phase is fascinating because after we activate the monitor process, we will usually find an absorbing finding of: Based on this information, we will be able to understand the real scope of the problem, the main characters of this attack and so on. This can be one of several values. ip4: ip6: include:. Microsoft Office 365. Test: ASF adds the corresponding X-header field to the message. Most end users don't see this mark. So before we can create the SPF record we first need to know which systems are sending mail on behalf of your domain, besides Office 365.
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