spf, dkim, dmarc best practices

SPF What are the best practices for SPF Management? We've included explanations and links to the official documentation and are dedicated to keeping this guide up-to-date and following the recommendations from the M3AAWG and cyber security specialists worldwide. DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; s=lufthansa5; d=fly-lh.lufthansa.com; We can see that Lufthansa is using five different keys (selectors) split over five separate subdomains of two primary production domains (lufthansa.com and milesandmore.com). Here are some best practices that you should follow when sending emails to Gmail accounts in order to avoid deliverability is an email authentication protocol that restricts who can send emails on your domains behalf. Use email authentication ideally all three of DKIM, DMARC, and SPF. Identify which messages sent from your organization pass or fail authentication checks (SPF or DKIM, or both). If you are using your own subdomains, you can sign with a single key, but make sure you set your adherence to DKIM to relaxed in the DMARC policy (adkim=r). Most often used optional parameters have to do with reporting: rua specifies a URL (either a mailto: or an http:// URL using POST method) to send daily aggregate reports on all failing messages purporting to come from a particular domain. DMARC So we advise against it. JetBlue uses Qualtrics analytics service, and the only thing they needed to do is include a correct SPF record from Qualtrics. Dont use a single key for all your clientsensure each client has a unique key. SPF is for limiting the servers that can send as your domain; DKIM is a newer alternative that includes verification of message integrity. In this article, well discuss the SPF, DKIM, and DMARC best practices. Similar problems arise from messages that are forwarded by just copying the original message over SMTP to the new recipient. To be on the safe side, you may want to quarantine all SPF-failing messages, and monitor the quarantine for a while, to make sure there are no false positives. The DMARC p tag addresses the DMARC policy mode. RFC7208 Sender Policy Framework This guide describes three predominant email authentication technologies in use today - SPF, DKIM, and DMARC, and discusses various aspects of their implementation. Once you pass the monitoring stage, you can escalate your policy to quarantine, and finally, to reject. Again, since DKIM does not allow for any policy specification, this will just verify the signature and insert an Authentication-Results header: Authentication-Results: mx1.hc4-93.c3s2.smtpi.com; dkim=pass (signature verified) header.i=MileagePlus@news.united.com. Detect and block suspicious IP addresses using your domain. SPF Their Sender Best Common Practices document is available at https://www.m3aawg.org/sites/maawg/files/news/M3AAWG_Senders_BCP_Ver3-2015-02.pdf. WebCopy article link What are DMARC, DKIM, and SPF? Some organizations believe that DMARC deployment is only valid for domains that are active and sending emails, but this isnt the case. SPF is for limiting the servers that can send as your domain; DKIM is a newer alternative that includes verification of message integrity. About the Internet Engineering Task Force (IETF) and the Internet Society, About Public Interest Registry (PIR) and the Internet Society, Network and Distributed System Security (NDSS) Symposium, Protecting the Internet against Fragmentation. DMARC With this policy, youll receive DMARC reports about all your sending sources and authentication status. SPF Make sure to check the box to send aggregate feedback reports this is arguably the most important feature of DMARC for the sender. Organizations should follow the regular DMARC enforcement route. Freddie Leeman Jan 10, 2023 3 min read The internet is evolving, and so are email security best practices. WebDMARC reports help you: Learn about all the sources that send email for your organization. Implement DMARC, initially in monitor mode to get receiver feedback and verify accuracy of email authentication, and eventually move to enforcement (signal a reject or quarantine policy to receivers). Microsoft 365 Defender. The DMARC protocol depends on both SPF and DKIM to authenticate email. [1] Canonicalization is beyond the scope of this document. Policy options are: 1) p=none 2) p=quarantine or 3) p=reject. Optionally, you can create DKIM Verification Profiles, and assign different Verification Profiles to different Mail Flow Policies. When you use the +all mechanism, your SPF record is essentially rendered useless, and any sender (including malicious actors) can deliver messages on your behalf. Also read the industry best practices document I linked. SPF verification is configured in Mail Flow Policies the easiest way to run it globally is to turn it on in the Default Policy Parameters section of the appropriate listener(s). postmaster@omp.news.united.com) identity=helo; x-sender="postmaster@omp.news.united.com"; Take note that for this message, two identities were verified by SPF: mailfrom as mandated by the specification, and helo as recommended by the same. DKIM or SPF both have their own pros and cons. The problem is that DMARC brought those issues to the surface by actively pushing a policy to reject the email, and by correlating all the different sender identifiers in a message. By default, ESA will verify up to five signatures. SPF DMARC DMARC In that case, you have two options: Although option #1is easier to start with, remember that it will ultimately break DMARC. DMARC is specified in RFC7489. Best Practice's DMARC validates the From address in each email, provides reporting mechanisms for valuable insights, and strengthens overall email authentication. on April 21, 2016. DMARC alignment helps to add a layer of security to your email channel by comparing the From Header to the DKIMs domain tag and SPFs return-path address. DKIM or SPF both have their own pros and cons. You should be upping spam scores of SPF failures unless it meets two of the scenarios I mentioned in my other comment. DMARC WebThe DKIM signature enables domain authentication to validate that the message was legitimately sent from the specified domain. DMARC DMARC Publish the key as generated in your DNS. In essence, it provides a simple way for a Domain Owner to advertise their legitimate email sources to the Receivers using DNS. DMARC Although it is not necessary for DKIM (messages for the same domain can be signed with multiple different keys), it is good practice to provide a separate subdomain for any email that is handled by a third-party. Sender authenticity is implied by having the From header signed. Implementing SPF, DKIM, and DMARC according to the best practices above will result in an optimal configuration that prevents third parties from spoofing your domain while simultaneously building the best possible reputation and guaranteeing legit emails reach their destination. It stands for DKIM alignment mode. SPF and DMARC are simple DNS records. Organizations should follow the regular DMARC enforcement route. DMARC ensures the destination email systems trust messages sent from your domain. Recently there has been a significant surge in SPF popularity, but many domains publish incomplete or incorrect SPF records. They also include instructions to Hard Fail any messages not authenticated by SPF (-all qualifier). Implement both SPF and DKIM for top-level domains, parked domains (not used for email) and any major subdomains seen on websites or used for email. However, this is only possible with proper DMARC configuration. For an email to pass the DMARC (Domain-based Message Authentication Reporting and Conformance), it needs to either pass and align SPF (Sender Policy Framework) or pass and align DKIM (DomainKeys Identified Mail). Because email can still be authenticated with DKIM and pass DMARC even if SPF fails. For a message to pass DKIM Verification, any signatures need to verify. Otherwise, hackers can exploit them for cybercrimes, which can spoil your domains reputation, business reputation, and credibility. However, it is then your responsibility to keep those records accurate, and if the provider adds additional gateways or changes IP addresses or hostnames, your mail flow may be jeopardized. Although in general more is better, you must take into account that creating two digital signatures per message (including canonicalization, etc.) As we can see, Sun Country has some of their emails under their own control, but their marketing email is outsourced to a third-party. By default, a particular domains DMARC policy applies to all of its subdomains. 2:30 minute read. According to specification, a receiver must adhere to the advertised policy. DMARC What are DMARC Tags To deploy DKIM, you should create one or more public keys and publish them in your DKIM record so that the email receiver can easily retrieve it to validate the signature. As a message passes multiple gateways, it can be signed multiple times and thus carry multiple signatures. The DMARC protocol depends on both SPF and DKIM to authenticate email. Another improvement of DMARC over previous email authentication technologies is how it handles subdomains. DKIM instead identifies senders using an encryption key with a digital signature to ensure that mail is safe. The authenticating domain must be the same domain that's in the message From: header. Its no news that the DKIM email authentication protocol leverages cryptographic digital signatures to prove the legitimacy of a message. SPF allows email senders to define which IP addresses can send mail, while DKIM uses an encryption key and digital signature to verify an email. This may include regularly checking your SPF and DKIM records, monitoring your email logs, and testing your email infrastructure to identify any issues. View with Adobe Reader on a variety of devices, View in various apps on iPhone, iPad, Android, Sony Reader, or Windows Phone, View on Kindle device or Kindle app on multiple devices, Domain-based Message Authentication, Reporting And Conformance (DMARC), If You Provide Email Services For Other Domains Or Third-Parties, Sample Action Plan To Implement Email Authentication, https://otalliance.org/resources/spf-dmarc-record-validator, http://www.kitterman.com/dmarc/assistant.html, http://www.kitterman.com/spf/validate.html, https://www.ciscolive.com/online/connect/sessionDetail.ww?SESSION_ID=76627, https://www.m3aawg.org/sites/maawg/files/news/M3AAWG_Senders_BCP_Ver3-2015-02.pdf, Making sure that all available identities (HELO, MAIL FROM and/or DKIM signing domain) are aligned (exactly matching or subordinate) with From header, Providing a means for the sender domain owner to specify a policy for receivers on how they, Providing a feedback facility for sender domain owners to be informed of any failing messages thus making it easy to identify phishing campaigns or errors in SPF/DKIM/DMARC policy assignment, Use a single Signing Profile to sign for all domains. It directs the receiver to report, quarantine, or reject emails that fail authentication checks. Implement opportunistic TLS to protect email in transit between mail servers. SPF and DMARC are simple DNS records. Authors of DKIM suggest several solutions to the problem, all of which boil down to the mailing list managers having to use the address of the list in all From addresses, andindicating the original sender address by another means. Take note that senders do not specify what receivers should do with failing messages, just to which degree they will fail. SPF allows email senders to define which IP addresses can send mail, while DKIM uses an encryption key and digital signature to verify an email. Similarly to the previous paragraph, if you are using any third-party emailing services, and wish to establish fully SPF-verified mail flow, you must include their own SPF records in yours. This guide describes three predominant email authentication technologies in use today - SPF, DKIM, and DMARC, and discusses various aspects of their implementation. Together, they help prevent spammers, phishers, and other unauthorized parties from sending emails on behalf of a domain * they do not own. Best Practice for Email Authentication - Optimal Ways DMARC DMARC This means that senders will experience consistent authentication results for their messages at AOL, Gmail, Hotmail, Yahoo! Security Factsheet: Why Should Municipalities Make Network and Data Security a Priority? At EasyDMARC, weve made the process easy for you with our suite of innovative tools, such as the. This is done using Message Filter rule SPF-status() [3], or by creating an Incoming Content Filter using the same and applying it to appropriate Incoming Mail Policies. This error is most often done by applications that send email notifications or warnings because application authors are mostly unaware of the consequences of the inconsistency of their email identities. Ensure that domains are locked to prevent domain takeovers. SPF doesn't use an encryption algorithm, while DKIM uses an encryption algorithm However, simply configuring these protocols isnt enough; you must follow the best practices to ensure optimal function and robust email security. This technique was often employed by ESPs in the past it allowed them to sign on a large scale, while not having to interact with individual customers DNS space. Ultimately, SPF and DKIM ensure that your reputation stays high, and that your cold email shows up when and where you want it. If you are using the same listener for incoming and outgoing mail collection, make sure that your RELAYED Mail Flow Policy has SPF verification set to Off. We'll dedicate a separate blog on how to implement SPF macros soon. Additionally, to enable correct report generation, you will need to edit "Global Settings" of the DMARC section of "Mail Policies". WebCopy article link What are DMARC, DKIM, and SPF? When an email is sent to a mailing list, it is redistributed to all of its recipients. SPF identifies IP addresses in order to determine which senders are permitted to send mail to a domain. Some organizations use DKIM keys they created several years ago, which isnt a good idea. Gmail [2] DKIM DNS record parameters are also out of scope of this document. If you are still in the early stages of DMARC implementation, start with a p=none policy and use URIports to monitor your email traffic through DMARC reports. Also, worth noting is that all of the above examples make extensive use of additional DNS referrals (include mechanisms). DMARC, SPF,DKIM, and BIMI records, EasyDMARC Inc. 2023 | All Rights Reserved. Gmail M3AAWG Protecting Parked Domains Best Common Practices, RFC7489 Domain-based Message Authentication, Reporting, and Conformance, RFC6376 DomainKeys Identified Mail Signatures, RFC8301 Cryptographic Algorithm and Key Usage Update to DKIM, M3AAWG Best Practices for Implementing DKIM, M3AAWG Email Authentication Recommended Best Practices, M3AAWG DKIM Key Rotation Best Common Practices, SPF record should not exceed the 10 DNS lookup limit, SPF records should not authorize more sources than necessary, Sign all outbound emails with a domain that aligns with the, The policy should be set to reject where possible (. SPF Several real-life email architecture situations are discussed, and guidelines for implementing them on the Cisco Email Security product set. URIports can even send (push-) notifications when irregularities are detected, avoiding the dreadful task of regularly and manually checking the DMARC report data. Once (most of) your email sources have been identified, you may want to take a step back, and instead of authorizing every single existing source, clean up the list. For smaller organizations and those with controlled mail flows it will be fairly straightforward, while larger environments may find it exceptionally challenging. Since this is a hands-on best practices guide, some of the more complex material will be omitted. They also provide a separate SPF record for their vendors in _spf.vendor.delta.com. OTA recognizes the critical role email plays in todays online ecosystem, and publishes the following recommendations: The Policy Toolkit on IoT Security and Privacy is a practical resource for policymakers and regulators to strengthen the For many of us the Internet is a staple in our day-to-day lives especially at our jobs. Configuring DKIM verification on the ESA is similar to SPF verification. This indicates that they are currently in the monitor phase of DMARC deployment. In general, if you are providing email services for a larger number of third-parties that you dont have direct control over, it is good practice to write a guideline document on how to submit an email that is most likely to deliver. Implement Distributed Denial of Service (DDoS) mitigation technologies and processes. It will make tracking the messages easier, and will allow for much cleaner implementation of DMARC later on. However, such reports come in XML format, so theyre hard to understand and analyze. When implementing a DMARC record, you have 3 policy options. They allow you to limit key sizes of signatures you will accept, set key retrieval failure actions and configure the depth of DKIM verification. DMARC verification will add additional fields to the Authentication-Results header: Authentication-Results: mx1.hc4-93.c3s2.smtpi.com; dkim=pass (signature verified) header.i=MileagePlus@news.united.com; dmarc=pass (p=none dis=none) d=news.united.com. DKIM or SPF both have their own pros and cons. Basically, SPF, along with DKIM, DMARC, and other technologies supported by Office 365, help prevent spoofing and phishing. SPF Microsoft 365 Defender. Optimize SPF records with no more than 10 DNS lookups.
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