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. Enabling one or more of the ASF settings is an aggressive approach to spam filtering. This defines the TXT record as an SPF TXT record. Include the following domain name: spf.protection.outlook.com. 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. The rest of this article uses the term SPF TXT record for clarity. Q8: Who is the element which is responsible for alerting users regarding a scenario in which the result of the SPF sender verification test is 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. This article describes how to update a Domain Name Service (DNS) record so that you can use Sender Policy Framework (SPF) email authentication with your custom domain in Office 365. If you're using IPv6 IP addresses, replace ip4 with ip6 in the examples in this article. The E-mail address of the sender uses the domain name of a well-known bank. Nearly all large email services implement traditional SPF, DKIM, and DMARC checks. 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. Included in those records is the Office 365 SPF Record. Q10: Why our mail server doesnt automatically block incoming E-mail that has the value of SPF = Fail? We do not recommend disabling anti-spoofing protection. - last edited on 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. 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. ip6 indicates that you're using IP version 6 addresses. In other words, using SPF can improve our E-mail reputation. 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. Oct 26th, 2018 at 10:51 AM. Creating multiple records causes a round robin situation and SPF will fail. EOP includes a default spam filter policy, which includes various options that enable us to harden the existing mail security policy. 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. Once you have formed your SPF TXT record, you need to update the record in DNS. 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. You can identify messages that were filtered by ASF by: The following sections describe the ASF settings and options that are available in anti-spam policies in the Microsoft 365 Defender portal, and in Exchange Online PowerShell or standalone EOP PowerShell (New-HostedContentFilterPolicy and Set-HostedContentFilterPolicy). Office 365 supports only one SPF record (a TXT record that defines SPF) for your domain. 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". 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. This article provides frequently asked questions and answers about anti-spoofing protection for Microsoft 365 organizations with mailboxes in Exchange Online, or standalone Exchange Online Protection (EOP) organizations without Exchange Online mailboxes. 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. Below is an example of adding the office 365 SPF along with onprem in your public DNS server. Learning/inspection mode | Exchange rule setting. This is no longer required. 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. This ASF setting is no longer required. If you go over that limit with your include, a-records an more, mxtoolbox will show up an error! If you haven't already done so, form your SPF TXT record by using the syntax from the table. For more information, see Configure anti-spam policies in EOP. 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. This ASF setting is no longer required. To do this, contoso.com publishes an SPF TXT record that looks like this: When the receiving server sees this record in DNS, it also performs a DNS lookup on the SPF TXT record for contoso.net and then for contoso.org. 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). Otherwise, use -all. The number of messages that were misidentified as spoofed became negligible for most email paths. You need some information to make the record. 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. I am using Cloudflare, if you dont know how to change or add DNS records, then contact your hosting provider. SPF helps validate outbound email sent from your custom domain (is coming from who it says it is). 04:08 AM 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. 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. What are the possible options for the SPF test results? When the receiving messaging server gets a message from joe@contoso.com, the server looks up the SPF TXT record for contoso.com and finds out whether the message is valid. Gather this information: The SPF TXT record for your custom domain, if one exists. 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. One of the options that can be activated is an option named SPF record: hard fail. By default, this option is not activated. When it finds an SPF record, it scans the list of authorized addresses for the record. 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. To avoid this, you can create separate records for each subdomain. 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. You will need to create an SPF record for each domain or subdomain that you want to send mail from. The Exchange rule includes three main parts: In our specific scenario, we will use the Exchange rule using the following configuration setting-, Phase 1. Share. 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. Test mode is not available for the following ASF settings: Microsoft 365 organizations with Exchange Online mailboxes. This is because the receiving server cannot validate that the message comes from an authorized messaging server. 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. Per Microsoft. 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. What is the conclusion such as scenario, and should we react to such E-mail message? You can also specify IP address ranges using CIDR notation, for example ip4:192.168.0.1/26. What is SPF? We reviewed the need for completing the missing part of our SPF implementation, in which we need to capture an event of SPF sender verification test in which the result is fail and, especially, in a scenario in which the sender E-mail address includes our domain name (most likely certainly a sign that this is a Spoof mail attack). The SPF information identifies authorized outbound email servers. See Report messages and files to Microsoft. Misconception 1: Using SPF will protect our organization from every scenario in which hostile element abuses our organizational identity. 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. We recommend that you disable this feature as it provides almost no additional benefit for detecting spam or phishing message, and would instead generate mostly false positives. For questions and answers about anti-malware protection, see Anti-malware protection FAQ. In the next two articles (Implementing SPF Fail policy using Exchange Online rule (dealing with Spoof E-mail attack) | Phase 1 learning mode | Part 2#3 and Implementing SPF Fail policy using Exchange Online rule (dealing with Spoof E-mail attack) | Phase 2 production | part 3#3), we will review in details the implementation of SPF fail policy by using an Exchange Online rule. A9: The answer depends on the particular mail server or the mail security gateway that you are using. The first one reads the "Received-SPF" line in the header information and if it says "SPF=Fail" it sends the message to quarantine. SPF identifies which mail servers are allowed to send mail on your behalf. We will review how to enable the option of SPF record: hard fail at the end of the article. 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. A scenario in which hostile element spoofs the identity of a legitimate recipient, and tries to attack our organization users. Learn about who can sign up and trial terms here. 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. It doesn't have the support of Microsoft Outlook and Office 365, though. Anti-spoofing protection considers both SPF hard fails and a much wider set of criteria. Also, if your custom domain does not have an SPF TXT record, some receiving servers may reject the message outright. Microsoft itself first adopted the new email authentication requirements several weeks before deploying it to customers. However, the industry is becoming more aware about issues with unauthenticated email, particularly because of the problem of phishing. To work around this problem, use SPF with other email authentication methods such as DKIM and DMARC.
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