--- title: "Alert: Fix SPF & DKIM Settings For Your Email Forwarding Set Up Through Microsoft o365 SMTP Server Or Your Emails May End Up In Spam | DuoCircle" description: "Microsoft is making some changes to harden the configuration for emails relayed or forwarded through Office 365 SMTP server(s)." image: "https://www.duocircle.com/images/og-default.png" canonical: "https://www.duocircle.com/blog/announcements/alert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam/" --- Quick Answer Starting July 27, 2021 Microsoft routed forwarded or relayed mail through the Regular Relay Pool (high-risk delivery, IPs in 40.95.0.0/16, hostnames containing rly) unless the message met three conditions: the outbound sender domain is an accepted domain, SPF passes at the o365 server, and DKIM passes. Otherwise expect spam folder placement. Share [ ](https://www.linkedin.com/sharing/share-offsite/?url=undefined%2Fblog%2Fannouncements%2Falert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=Alert%3A%20Fix%20SPF%20%26%20DKIM%20Settings%20For%20Your%20Email%20Forwarding%20Set%20Up%20Through%20Microsoft%20o365%20SMTP%20Server%20Or%20Your%20Emails%20May%20End%20Up%20In%20Spam&url=undefined%2Fblog%2Fannouncements%2Falert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=undefined%2Fblog%2Fannouncements%2Falert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam%2F "Share on Facebook") [ ](https://reddit.com/submit?url=undefined%2Fblog%2Fannouncements%2Falert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam%2F&title=Alert%3A%20Fix%20SPF%20%26%20DKIM%20Settings%20For%20Your%20Email%20Forwarding%20Set%20Up%20Through%20Microsoft%20o365%20SMTP%20Server%20Or%20Your%20Emails%20May%20End%20Up%20In%20Spam "Share on Reddit") [ ](mailto:?subject=Alert%3A%20Fix%20SPF%20%26%20DKIM%20Settings%20For%20Your%20Email%20Forwarding%20Set%20Up%20Through%20Microsoft%20o365%20SMTP%20Server%20Or%20Your%20Emails%20May%20End%20Up%20In%20Spam&body=Check out this article: undefined%2Fblog%2Fannouncements%2Falert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam%2F "Share via Email") ![spam](https://media.mailhop.org/duocircle/images/2021/07/sender-policy-framework-7535.jpg) _Microsoft is making some changes to harden the configuration for emails relayed or forwarded through Office 365 SMTP server(s)._ Starting July 27, 2021, they will be updating **_Special Relay Pools_**, a separate IP address pool used for relayed or forwarded emails sent from domains that do not come under _accepted domains_ in your tenant. Till July 26, 2021, they will be redirecting forwarded and relayed emails from all the domains (including those which do not come under accepted ones). However, the forwarded emails will no longer be directed through special replay pools but **_Regular Relay Pools_** (or high-risk delivery pools) after the mentioned date\_.\_ ## How This Will Impact Your Organization When the changes mentioned above are implemented, messages that do not meet the below-given criteria will route through the [_Regular Relay Pool_](https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/high-risk-delivery-pool-for-outbound-messages?view=o365-worldwide). Resultantly, the emails might end up in the recipient’s spam. | 1\. Outbound sender domain must be an accepted domain of the tenant. 2\. [SPF check](https://www.duocircle.com/email/spf-record-check) is passed when the email comes to the Microsoft o365 server. 3\. [DKIM](https://www.duocircle.com/resources/what-is-dkim) is passed when the email comes to the Microsoft o365 server. | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | Emails that meet the above criteria will not be relayed through the Regular Relay Pool. However, the [SRS](https://docs.microsoft.com/en-us/office365/troubleshoot/antispam/sender-rewriting-scheme) rewrite will be skipped for forwarded emails (that do not pass the above-mentioned three-point criteria). _In essence, emails sent from domains that are not accepted domains in your tenant will be impacted by this change._ [![forwarded emails](https://media.mailhop.org/duocircle/images/2021/07/spf-record-check-7536.jpg)](https://media.mailhop.org/duocircle/images/2021/07/spf-record-check-7536.jpg) ## What You Can Do To Prepare For This Change When the changes are in effect, you can identify if an email was sent via the Relay Pool either by: 1. Going through the **outbound server IP** (The IP range of all Regular Relay Pool will be 40.95.0.0/16) or 2. Observing the outbound server name (which will have “rly” in the name). For the emails to go through the Regular Relay Pool, _you will need to ensure that they pass SPF and DKIM checks or the sender domain of the outbound message matches an accepted domain of your tenant._ ## Additional Info: How To Enable DKIM For Your Domain(s) & Add Custom Domains To comply with the above changes, ensure you enable DKIM for the _sending domain(s);_ for example, say yoursecondarydomain.com is part of yourprimarydomain.com accepted domains. Then if the sending address is [sender@yoursecondarydomain.com](mailto:sender@yoursecondarydomain.com), the DKIM needs to be enabled for yoursecondarydomain.com. For more information on _how you can enable DKIM on Microsoft o365, you can go through [here](https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/use-dkim-to-validate-outbound-email?view=o365-worldwide#steps-to-manually-set-up-dkim)_. To add custom domains, you can follow the steps outlined [here](https://docs.microsoft.com/en-us/microsoft-365/admin/setup/add-domain?view=o365-worldwide). [![DKIM on Microsoft o365](https://media.mailhop.org/duocircle/images/2021/07/spf-permerror-7537.jpg)](https://media.mailhop.org/duocircle/images/2021/07/spf-permerror-7537.jpg) ## Final Words If you use Microsoft o365 SMTP server for forwarding or relaying emails, _it is strongly recommended to make the changes as mentioned above **before July 27, 2021**_, or your emails may have to suffer going through Regular Relay Pools (or high-risk relay pools), where _there is no guarantee that emails would land up in the desired inbox folder_, and not in spam/junk folders. Besides, if you want to avoid this hassle altogether, you can consider switching to DuoCircle’s [reliable SMTP server](/email/outbound-smtp) as your **outbound relay** and can rest assured that all your emails will be delivered via a dedicated or good reputation IP only so they always land in recipients’ primary mailbox only. [Fix your DKIM on Office 365](/email/dmarc) ## Topics NewsSecurityUpdates ![Brad Slavin](https://media.mailhop.org/dmarcreport/images/team/brad-slavin.jpg) Brad Slavin General Manager General Manager at DuoCircle. Product strategy and commercial lead across the email security portfolio. ## Secure your email infrastructure Protect, authenticate, and deliver. Contact our team to find the right solution. [Contact Sales](/contact/) [Explore Products](/products/) ## Related Articles [ News 6m Cyber Security News Update, Week 1 of 2022 Jan 7, 2022 ](/blog/announcements/cyber-security-news-update-week-1-of-2022/)[ News 7m Cybersecurity News Update, Week 1 of 2023 Jan 1, 2023 ](/blog/announcements/cyber-security-news-update-week-1-of-2023/)[ News 5m EasyPark Data Breach, Ohio Lottery Cyberattack, GTA 5 Leak, Cybersecurity News \[December 25, 2023\] Jan 4, 2024 ](/blog/announcements/cyber-security-news-update-week-1-of-2024/)[ News 6m Microsoft Cybersecurity Transparency, Chrome Update Required, Google Calendar Phishing, Cybersecurity News \[December 23, 2024\] Jan 2, 2025 ](/blog/announcements/cyber-security-news-update-week-1-of-2025/) ```json {"@context":"https://schema.org","@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}],"sameAs":["https://www.linkedin.com/company/duocircle","https://x.com/duocirclellc","https://www.facebook.com/duocirclellc","https://www.g2.com/products/phish-protection-by-duocircle/reviews","https://github.com/duocircle","https://www.crunchbase.com/organization/duocircle-llc"],"contactPoint":{"@type":"ContactPoint","contactType":"customer support","url":"https://support.duocircle.com"},"knowsAbout":["Email Security","Email Authentication","SPF","DKIM","DMARC","Phishing Protection","Spam Filtering","SMTP Relay","Email Deliverability","Email Forwarding"]} ``` ```json {"@context":"https://schema.org","@type":"WebSite","name":"DuoCircle LLC","url":"https://www.duocircle.com","description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","publisher":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}]}} ``` ```json [{"@context":"https://schema.org","@type":"BlogPosting","headline":"Alert: Fix SPF & DKIM Settings For Your Email Forwarding Set Up Through Microsoft o365 SMTP Server Or Your Emails May End Up In Spam","description":"Microsoft is making some changes to harden the configuration for emails relayed or forwarded through Office 365 SMTP server(s).","url":"https://www.duocircle.com/blog/announcements/alert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam/","datePublished":"2021-07-20T13:28:53.000Z","dateModified":"2025-05-23T12:52:24.000Z","dateCreated":"2021-07-20T13:28:53.000Z","author":{"@type":"Person","@id":"https://www.duocircle.com/authors/brad-slavin/#person","name":"Brad Slavin","url":"https://www.duocircle.com/authors/brad-slavin/","jobTitle":"General Manager","description":"Brad Slavin runs DuoCircle, the company behind DMARC Report, AutoSPF, Phish Protection, and Mailhop. His focus is product strategy, customer relationships, and the commercial and compliance side of email authentication (DPAs, SLAs, enterprise procurement).","image":"https://media.mailhop.org/dmarcreport/images/team/brad-slavin.jpg","knowsAbout":["Email Security Strategy","SaaS Product Management","Enterprise Compliance","Customer Success","Email Deliverability Business"],"worksFor":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com"},"sameAs":["https://www.linkedin.com/in/bradslavin"]},"publisher":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}]},"mainEntityOfPage":{"@type":"WebPage","@id":"https://www.duocircle.com/blog/announcements/alert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam/"},"articleSection":"announcements","keywords":"News, Security, Updates","wordCount":532,"image":{"@type":"ImageObject","url":"https://media.mailhop.org/duocircle/images/2021/07/sender-policy-framework-7535.jpg","caption":"spam","width":900,"height":600},"speakable":{"@type":"SpeakableSpecification","cssSelector":[".answer-block","h1"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Blog","item":"https://www.duocircle.com/blog/"},{"@type":"ListItem","position":2,"name":"News"},{"@type":"ListItem","position":3,"name":"Alert: Fix SPF & DKIM Settings For Your Email Forwarding Set Up Through Microsoft o365 SMTP Server Or Your Emails May End Up In Spam","item":"https://www.duocircle.com/blog/announcements/alert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam/"}]}] ``` ```json {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://www.duocircle.com/"},{"@type":"ListItem","position":2,"name":"Blog","item":"https://www.duocircle.com/blog/"},{"@type":"ListItem","position":3,"name":"News","item":"https://www.duocircle.comundefined"},{"@type":"ListItem","position":4,"name":"Alert: Fix SPF & DKIM Settings For Your Email Forwarding Set Up Through Microsoft o365 SMTP Server Or Your Emails May End Up In Spam","item":"https://www.duocircle.com/blog/announcements/alert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam/"}]} ``` ```json {"@context":"https://schema.org","@type":"BlogPosting","headline":"Alert: Fix SPF & DKIM Settings For Your Email Forwarding Set Up Through Microsoft o365 SMTP Server Or Your Emails May End Up In Spam","description":"Microsoft is making some changes to harden the configuration for emails relayed or forwarded through Office 365 SMTP server(s).","url":"https://www.duocircle.com/blog/announcements/alert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam/","datePublished":"2021-07-20T13:28:53.000Z","dateModified":"2025-05-23T12:52:24.000Z","dateCreated":"2021-07-20T13:28:53.000Z","author":{"@type":"Person","@id":"https://www.duocircle.com/authors/brad-slavin/#person","name":"Brad Slavin","url":"https://www.duocircle.com/authors/brad-slavin/","jobTitle":"General Manager","description":"Brad Slavin runs DuoCircle, the company behind DMARC Report, AutoSPF, Phish Protection, and Mailhop. His focus is product strategy, customer relationships, and the commercial and compliance side of email authentication (DPAs, SLAs, enterprise procurement).","image":"https://media.mailhop.org/dmarcreport/images/team/brad-slavin.jpg","knowsAbout":["Email Security Strategy","SaaS Product Management","Enterprise Compliance","Customer Success","Email Deliverability Business"],"worksFor":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com"},"sameAs":["https://www.linkedin.com/in/bradslavin"]},"publisher":{"@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. We deliver about 90% of category-leader capability at roughly half the price, backed by experts who own the outcome. Trusted by 50,000+ organizations since 2014.","subOrganization":[{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138898167","name":"DMARC Report","url":"https://dmarcreport.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897474","name":"AutoSPF","url":"https://autospf.com"},{"@type":"Organization","@id":"https://www.wikidata.org/wiki/Q138897912","name":"Phish Protection","url":"https://www.phishprotection.com"}]},"mainEntityOfPage":{"@type":"WebPage","@id":"https://www.duocircle.com/blog/announcements/alert-fix-spf-dkim-settings-for-your-email-forwarding-set-up-through-microsoft-o365-smtp-server-or-your-emails-may-end-up-in-spam/"},"articleSection":"announcements","keywords":"News, Security, Updates","wordCount":532,"image":{"@type":"ImageObject","url":"https://media.mailhop.org/duocircle/images/2021/07/sender-policy-framework-7535.jpg","caption":"spam","width":900,"height":600},"speakable":{"@type":"SpeakableSpecification","cssSelector":[".answer-block","h1"]}} ```