In order to use a custom domain, Office 365 requires that you add a Sender Policy Framework (SPF) TXT record to your DNS record to help prevent spoofing. We do not recommend disabling anti-spoofing protection. Disable SPF Check On Office 365. Although SPF is designed to help prevent spoofing, but there are spoofing techniques that SPF can't protect against. Include the following domain name: spf.protection.outlook.com. 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. Identify a possible miss configuration of our mail infrastructure. Another distinct advantage of using Exchange Online is the part which enables us to select a very specific response (action), that will suit our needs such as Perpend the E-mail message subject, Send warning E-mail, send the Spoof mail to quarantine, generate the incident report and so on. Given that we are familiar with the exact structure of our mail infrastructure, and given that we are sure that our SPF record includes the right information about our mail servers IP address, the conclusion is that there is a high chance that the E-mail is indeed spoofed E-mail! 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. 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. Messages sent from an IP address that isn't specified in the SPF Sender Policy Framework (SPF) record in DNS for the source email domain are marked as high confidence spam. 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. If you provided a sample message header, we might be able to tell you more. First, we are going to check the expected SPF record in the Microsoft 365 Admin center. This change should reduce the risk of SharePoint Online notification messages ending up in the Junk Email folder. Q5: Where is the information about the result from the SPF sender verification test stored? Once you've formed your record, you need to update the record at your domain registrar. SPF is configured by adding a specially formatted TXT record to the DNS zone for the domain. Keeping track of this number will help prevent messages sent from your organization from triggering a permanent error, called a perm error, from the receiving server. Phishing emails Fail SPF but Arrive in Inbox Posted by enyr0py 2019-04-23T19:01:42Z. Per Microsoft. After a specific period, which we allocate for examining the information that collected, we can move on to the active phase, in which we execute a specific action in a scenario that the Exchange rule identifies an E-mail message that is probably Spoof mail. For advanced examples and a more detailed discussion about supported SPF syntax, see How SPF works to prevent spoofing and phishing in Office 365. You can use nslookup to view your DNS records, including your SPF TXT record. - last edited on This improved reputation improves the deliverability of your legitimate mail. This tag allows the embedding of different kinds of documents in an HTML document (for example, sounds, videos, or pictures). A hard fail, for example, is going to look like this: v=spf1 ip4 192.xx.xx.xx -all If mail is being sent from another server that's not the IP in the SPF, the receiving server will discard it. Update your SPF TXT record if you are hitting the 10 lookup limit and receiving errors that say things like, "exceeded the lookup limit" and "too many hops". Vs. this scenario, in a situation in which the sender E-mail address includes our domain name, and also the result from the SPF sender verification test is fail, this is a very clear sign of the fact that the particular E-mail message has a very high chance to consider as Spoof mail. The SPF information identifies authorized outbound email servers. By analyzing the information thats collected, we can achieve the following objectives: 1. SPF (Sender Policy Framework) is an email authorization protocol that checks the sender's IP address against a list of IPs published on the domain used as the Return-Path header of the email sent. Once a message reaches this limit, depending on the way the receiving server is configured, the sender may get a message that says the message generated "too many lookups" or that the "maximum hop count for the message has been exceeded" (which can happen when the lookups loop and surpass the DNS timeout). A1: A Spoof mail attack implemented when a hostile element, uses a seemingly legitimate sender identity. DMARC email authentication's goal is to make sure that SPF and DKIM information matches the From address. If you don't use a custom URL (and the URL used for Office 365 ends in onmicrosoft.com), SPF has already been set up for you in the Office 365 service. An SPF record is required for spoofed e-mail prevention and anti-spam control. Sender Policy Framework, or SPF, is an email authentication technique that helps protect email senders and recipients from spam, phishing and spoofing. v=spf1 ip4:10.10.10.1/16 mx ptr:Sender.domain.com include:spf.protection.outlook.com ~all. If you have a custom domain or are using on-premises Exchange servers along with Microsoft 365, you need to manually set up DMARC for your outbound mail. This record probably looks like this: If you're a fully hosted customer, that is, you have no on-premises mail servers that send outbound mail, this is the only SPF TXT record that you need to publish for Office 365. 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. Scenario 1. A2: The purpose of using the identity of one of our organization users is because, there is a high chance that the Innocent victim (our organization user), will tend to believe someone he knows vs. some sender that he doesnt know (and for this reason tends to trust less). Scenario 2 the sender uses an E-mail address that includes. When this mechanism is evaluated, any IP address will cause SPF to return a fail result. Conditional Sender ID filtering: hard fail. Previously, you had to add a different SPF TXT record to your custom domain if you also used SharePoint Online. More info about Internet Explorer and Microsoft Edge. Can we say that we should automatically block E-mail message which their organization doesnt support the use of SPF? For questions and answers about anti-malware protection, see Anti-malware protection FAQ. Microsoft maintains a dynamic but non-editable list of words that are associated with potentially offensive messages. I hate spam to, so you can unsubscribe at any time. Sender Policy Framework (SPF) allows email administrators to reduce sender-address forgery (spoofing) by specifying which are allowed to send email for a domain. This ASF setting is no longer required. Most of the time, I dont recommend executing a response such as block and delete E-mail that was classified as spoofing mail because the simple reason is that probably we will never have full certainty that the specific E-mail message is indeed spoofed mail. 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. A4: The sender E-mail address, contains information about the domain name (the right part of the E-mail address). To defend against these, once you've set up SPF, you should configure DKIM and DMARC for Office 365. SPF is designed to help prevent spoofing, but there are spoofing techniques that SPF can't protect against. Indicates soft fail. 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. Depending on the property, ASF detections will either mark the message as Spam or High confidence spam. SPF identifies which mail servers are allowed to send mail on your behalf. 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. 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. How to deal with a Spoof mail attack using SPF policy in Exchange-based environment, Exchange Online | Using the option of the spam filter policy, How to configure Exchange Online spam filter policy to mark SPF fail as spam, Implementing SPF Fail policy using Exchange Online rule (dealing with Spoof E-mail attack) | Phase 1 learning mode, Implementing SPF Fail policy using Exchange Online rule (dealing with Spoof E-mail attack) | Phase 2 production, Implementing SPF Fail policy using Exchange Online rule (dealing with Spoof E-mail attack) | Phase 1 learning mode | Part 2#3, Implementing SPF Fail policy using Exchange Online rule (dealing with Spoof E-mail attack) | Phase 2 production | part 3#3), Submit a request for removing your mail server IP from Office 365 black list, My E-mail appears as spam | Troubleshooting Mail server | Part 14#17, Detect spoof E-mail and add disclaimer using Exchange Online rule |Part 6#12, Create unlimited Client Secret in Azure AD, Configure Certificate Based Authentication to run automated PowerShell scripts, Implementing SPF Fail policy using Exchange Online rule (dealing with Spoof E-mail attack) | Introduction (this article), Case 1 a scenario in which the hostile element uses the spoofed identity of a, Case 2 a scenario in which the hostile element uses a spoofed identity of. If all of your mail is sent by Microsoft 365, use this in your SPF TXT record: In a hybrid environment, if the IP address of your on-premises Exchange Server is 192.168.0.1, in order to set the SPF enforcement rule to hard fail, form the SPF TXT record as follows: If you have multiple outbound mail servers, include the IP address for each mail server in the SPF TXT record and separate each IP address with a space followed by an "ip4:" statement. When Microsoft enabled this feature in 2018, some false positives happened (good messages were marked as bad). 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. Customers on US DC (US1, US2, US3, US4 . Scenario 1 the sender uses an E-mail address that includes a domain name of a well-known organization. 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. The SPF mechanism is not responsible for notifying us or, to draw our attention to events in which the result from the SPF sender verification test considered as Fail.. These are added to the SPF TXT record as "include" statements. 2. Office 365 supports only one SPF record (a TXT record that defines SPF) for your domain. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Q3: What is the purpose of the SPF mechanism? Use one of these for each additional mail system: Common. 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 these examples, contoso.com is the sender and woodgrovebank.com is the receiver. office 365 mail SPF Fail but still delivered Hello today i received mail from my organization. Mark the message with 'soft fail' in the message envelope. 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. 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). 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. Messages that contain numeric-based URLs (typically, IP addresses) are marked as spam. SPF, together with DKIM and DMARC helps to prevent spoofing of your mail domain. Indicates neutral. Recipient mail systems refer to the SPF TXT record to determine whether a message from your custom domain comes from an authorized messaging server. This phase is described as learning mode or inspection mode because the purpose of this step has been just to identify an event of a Spoof mail attack in which the hostile element uses an E-mail address that includes our domain name + Log this information. The SPF TXT record for Office 365 will be made in external DNS for any custom domains or subdomains. You intend to set up DKIM and DMARC (recommended). You will need to create an SPF record for each domain or subdomain that you want to send mail from. 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. 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. Typically, email servers are configured to deliver these messages anyway. Domain administrators publish SPF information in TXT records in DNS. We . Also, if you're only using SPF, that is, you aren't using DMARC or DKIM, you should use the -all qualifier. 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. Once you have formed your SPF TXT record, you need to update the record in DNS. In each of the above scenarios, the event in which the SPF sender verification test ended with SPF = Fail result is not good. To be able to react to the SPF events such as SPF = none (a scenario in which the domain doesnt include a dedicated SPF record) or a scene of SPF = Fail (a scene in which the SPF sender verification test failed), we will need to define a written policy that will include our desirable action + configure our mail infrastructure to use this SPF policy.. In this step, we want to protect our users from Spoof mail attack. GoDaddy, Bluehost, web.com) & ask for help with DNS configuration of SPF (and any other email authentication method). If you still like to have a custom DNS records to route traffic to services from other providers after the office 365 migration, then create an SPF record for . The organization publishes an SPF record (implemented as TXT record) that includes information about the IP address of the mail servers, which are authorized to send an E-mail message on behalf of the particular domain name. See You don't know all sources for your email. Now that Enhanced Filtering for Connectors is available, we no longer recommended turning off anti-spoofing protection when your email is routed through another service before EOP. Do nothing, that is, don't mark the message envelope. These scripting languages are used in email messages to cause specific actions to automatically occur. ASF specifically targets these properties because they're commonly found in spam. If an SPF TXT record exists, instead of adding a new record, you need to update the existing record. To get started, see Use DKIM to validate outbound email sent from your custom domain in Microsoft 365. 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. It is published as a Domain Name System (DNS) record for that domain in the form of a specially formatted TXT record. If you have a hybrid configuration (some mailboxes in the cloud, and . The Exchange rule includes three main parts: In our specific scenario, we will use the Exchange rule using the following configuration setting-, Phase 1. Find out more about the Microsoft MVP Award Program. This allows you to copy the TXT value and also check if your domain already has an SPF record (it will be listed as Invalid Entry). In order to help prevent denial of service attacks, the maximum number of DNS lookups for a single email message is 10. Read Troubleshooting: Best practices for SPF in Office 365. 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. Figure out what enforcement rule you want to use for your SPF TXT record. Exchange Online (EOP), include spam filter policy, which contains many security settings that are disabled by default and can be activated manually based on the particular mail security policy that the organization wants to implement. 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. The rest of this article uses the term SPF TXT record for clarity. Messages sent from Microsoft 365 to a recipient within Microsoft 365 will always pass SPF. Misconception 1: Using SPF will protect our organization from every scenario in which hostile element abuses our organizational identity. If you are a small business, or are unfamiliar with IP addresses or DNS configuration, call your Internet domain registrar (ex. Outlook.com might then mark the message as spam. Messages with no subject, no content in the message body, and no attachments are marked as high confidence spam. 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. All SPF TXT records start with this value, Office 365 Germany, Microsoft Cloud Germany only, On-premises email system. Messages that use JavaScript or Visual Basic Script Edition in HTML are marked as high confidence spam. Share. This is implemented by appending a -all mechanism to an SPF record. Use the 90-day Defender for Office 365 trial at the Microsoft 365 Defender portal trials hub. This is because the receiving server cannot validate that the message comes from an authorized messaging server. We recommend that you use always this qualifier. Use trusted ARC Senders for legitimate mailflows. The following examples show how SPF works in different situations. To do this, change include:spf.protection.outlook.com to include:spf.protection.outlook.de. The interesting thing is that in Exchange-based environment, we can use very powerful Exchange server feature named- Exchange rule, for identifying an event in which the SPF sender verification test result is Fail, and define a response respectively. There is no right answer or a definite answer that will instruct us what to do in such scenarios. Office 365 supports only one SPF record (a TXT record that defines SPF) for your domain. The SPF mechanism doesnt perform and concrete action by himself. 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. What is the recommended reaction to such a scenario? For example, vs. the Exchange Online spam filter policy that marks every incoming E-mail message that has the value of SPF = Fail as spam mail without distinction, when using the option of Exchange rule, we can define a more refined version of this scenario, a condition in which only if the sender uses our domain name + the result from the SPF verification test is Fail, only, then the E-mail message will be identified as Spoof mail. 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). You need some information to make the record. When you want to use your own domain name in Office 365 you will need to create an SPF record. The defense action that we will choose to implement in our particular scenario is a process in which E-mail message that identified as Spoof mail, will not be sent to the original destination recipient.. If you have any questions, just drop a comment below. Creating multiple records causes a round robin situation and SPF will fail. In other words, using SPF can improve our E-mail reputation. Required fields are marked *. More info about Internet Explorer and Microsoft Edge, Microsoft Defender for Office 365 plan 1 and plan 2, Set up SPF in Microsoft 365 to help prevent spoofing, Troubleshooting: Best practices for SPF in Microsoft 365, Example: SPF TXT record for multiple outbound on-premises mail servers and Microsoft 365, Use DKIM to validate outbound email sent from your custom domain in Microsoft 365, Use DMARC to validate email in Microsoft 365, Create DNS records at any DNS hosting provider for Microsoft 365. If you're the sender's email admin, make sure the SPF records for your domain at your domain registrar are set up correctly. Go to Create DNS records for Office 365, and then select the link for your DNS host. Soft fail. The answer is that as always; we need to avoid being too cautious vs. being too permissive. This list is known as the SPF record. In this category, we can put every event in which a legitimate E-mail message includes the value of SPF = Fail. 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. Text. This is no longer required. 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. To be able to send mail from Office 365 with your own domain name you will need to have SPF configured. Microsoft Office 365. For example, let's say that your custom domain contoso.com uses Office 365. As mentioned, the SPF sender verification test just stamp the E-mail message with information about the SPF test result. 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). Learning/inspection mode | Exchange rule setting. One option that is relevant for our subject is the option named SPF record: hard fail. The setting is located at Exchange admin Center > protection > spam filter > double click Default > advanced options > set SPF record: hard fail: off . In the current article, I want to provide you with a useful way, to implement a mail security policy related to an event in which the result of the SPF sender verification check is Fail. If we want to be more precise, an event in which the SPF sender verification test result is Fail, and the sender used the E-mail address, which includes our domain name. This applies to outbound mail sent from Microsoft 365. Need help with adding the SPF TXT record? Messages that contain hyperlinks that redirect to TCP ports other than 80 (HTTP), 8080 (alternate HTTP), or 443 (HTTPS) are marked as spam. 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. The first one reads the "Received-SPF" line in the header information and if it says "SPF=Fail" it sends the message to quarantine. Next, see Use DMARC to validate email in Microsoft 365. Hope this helps. Test: ASF adds the corresponding X-header field to the message. The most important purpose of the learning/inspection mode phase is to help us to locate cracks and grooves in our mail infrastructure. 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. This tag allows plug-ins or applications to run in an HTML window. TechCommunityAPIAdmin. 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. Anti-spoofing protection considers both SPF hard fails and a much wider set of criteria. A scenario in which hostile element spoofs the identity of a legitimate recipient, and tries to attack our organization users. For example, we are reasonable for configuring SPF record that will represent our domain and includes the information about all the mail server (the Hostname or the IP address) that can send E-mail on behalf of our domain name. The number of messages that were misidentified as spoofed became negligible for most email paths. SPF identifies which mail servers are allowed to send mail on your behalf. If you've already set up mail for Office 365, then you have already included Microsoft's messaging servers in DNS as an SPF TXT record. SPF validates the origin of email messages by verifying the IP address of the sender against the alleged owner of the sending domain. This article was written by our team of experienced IT architects, consultants, and engineers. Failing SPF will not cause Office 365 to drop a message, at best it will mark it as Junk, but even that wont happen in all scenarios. However, there are some cases where you may need to update your SPF TXT record in DNS.
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