Summary
When Outlook displays a phishing warning on emails sent through SendGrid from your CRM, it typically indicates a mismatch between the sender's apparent identity and the email's authentication. This often happens because Outlook's security mechanisms detect that an email purporting to be from your internal organization (e.g., your domain) is actually originating from an external service like SendGrid, even if SendGrid is authorized via SPF. The core issue usually revolves around how your domain's email authentication records (SPF, DKIM, and DMARC) are configured and whether they align with the sending practices of your third-party CRM and email service provider (ESP). Microsoft 365 (O365) employs advanced anti-phishing policies, including a feature to flag emails that spoof internal organization names or domains. These warnings are designed to protect users from business email compromise (BEC) attacks. To resolve this, you must ensure that your email authentication is correctly set up to explicitly authorize SendGrid to send emails on behalf of your domain, and that this authentication aligns with what Outlook expects for legitimate emails, particularly when they appear to be from within your organization.
Key findings
- Authentication Mismatch: The primary cause is often a perceived mismatch between the "From" address in the email header and the actual sending domain, particularly if the email originates from a third-party service like SendGrid. Outlook sees an email from yourdomain.com but the underlying authentication (like the DKIM signing domain or the SPF passing domain) points to sendgrid.net or a subdomain like sgsend.net.
- O365 Anti-Spoofing: Microsoft 365 has robust anti-spoofing and anti-phishing policies that flag emails appearing to be from an internal sender but coming from an external source. This is a common defense against Business Email Compromise (BEC) attacks.
- Admin Configuration: Such warnings can be enabled or configured by your Microsoft 365 administrator, indicating specific criteria for flagging emails as suspicious. Reviewing these internal settings is a crucial step.
- Domain Alignment: Proper DMARC (Domain-based Message Authentication, Reporting, and Conformance) alignment is key. DMARC requires that either the SPF or DKIM authenticated domain matches the domain in the "From" header of the email. If this alignment fails, emails are more likely to be flagged.
Key considerations
- SPF Record Configuration: While including include:sendgrid.net in your SPF record is a good start, ensuring it's correctly published and that no other SPF issues (like a TempError) are preventing proper verification is critical.
- DKIM Implementation: For emails sent via SendGrid, it is highly recommended to configure DKIM with your own domain (d=yourdomain.com) instead of SendGrid's default (d=sendgrid.net). This ensures DKIM alignment, significantly reducing phishing warnings. This is often referred to as whitelabeling or custom domain setup within SendGrid.
- DMARC Policy: Implement a DMARC policy for your domain. Even a p=none policy provides valuable insight into authentication failures via DMARC reports. Over time, you can progress to p=quarantine or p=reject once you are confident all legitimate mail is authenticated correctly. This strengthens your domain's reputation and helps prevent spoofing, which is what Outlook is trying to detect. You can find more details on Microsoft's recommendations for SPF failures on their Exchange Online Protection documentation.
- CRM Configuration: Ensure your CRM is configured to utilize the proper SendGrid integration that supports custom domain authentication for DKIM. Some CRM integrations might default to SendGrid's shared domain, which can cause these warnings.
- Internal Rules: Check if your O365 admin has implemented specific mail flow rules or anti-phishing policies that are triggering these warnings for emails from external sources that spoof internal display names. These rules might need to be adjusted or include exceptions for your SendGrid-sent emails once proper authentication is confirmed.
What email marketers say
Email marketers often encounter phishing warnings in Outlook when sending emails through third-party services like SendGrid, particularly when those emails appear to originate from an internal company address. Their experiences highlight the ongoing challenge of maintaining deliverability and inbox trust while leveraging external platforms for email outreach. Many marketers focus on the immediate impact on campaign performance and the perception of their brand when these warnings appear.The common thread among their discussions is the need to navigate the complexities of email authentication, especially as major email providers like Microsoft tighten their security protocols. They frequently look for quick fixes or direct guidance on configuring their sending platforms to avoid these disruptive alerts, balancing deliverability with the ease of use offered by their CRM and ESP integrations.
Key opinions
- Unexpected Warnings: Marketers express surprise and concern when emails that have historically delivered fine suddenly begin showing phishing warnings, especially for internal recipients.
- CRM Integration Impact: The issue often arises specifically for emails sent from their CRM, highlighting a potential disconnect in how the CRM handles email authentication compared to direct sends.
- SPF Inclusion Doubts: Some marketers question whether merely including sendgrid.net in their SPF record is sufficient, wondering if specific IPs or other configurations are missing.
- Admin Role: There's a recognition that internal IT or Microsoft 365 administrators play a crucial role, as they control the settings that trigger these warnings.
Key considerations
- Monitor Deliverability: Regularly monitor email deliverability, especially to Microsoft domains (Outlook, Hotmail, Live), to proactively identify and address issues. Our guide on Outlook and Hotmail deliverability provides further insights.
- Verify Authentication: Ensure your domain's SPF, DKIM, and DMARC records are correctly configured and aligned with SendGrid. This is foundational for preventing spoofing alerts. Resources like the MailBluster guide on spam and bounce emphasize this.
- Communicate with IT: Collaborate closely with your IT or O365 administrators to understand any custom anti-phishing rules and to ensure proper domain authentication is set up for SendGrid within your DNS.
- Custom Domain Sending: Always aim to configure SendGrid to send emails using your own domain for DKIM signing, rather than their shared domains. This is crucial for DMARC alignment and building a strong sender reputation, as discussed in our article why SendGrid emails go to spam on Outlook.com.
Marketer view
Marketer from Email Geeks notes that emails from their CRM, sent via SendGrid, have consistently shown a phishing warning in Outlook for about a week, specifically for internal accounts. This is a new development for them.They emphasize that these are emails from their own CRM, to internal recipients, making the sudden warning particularly perplexing and disruptive to internal communications.
Marketer view
Marketer from Email Geeks queries whether including sendgrid.net in the SPF record is sufficient or if specific IP addresses need to be listed. They express concern that the current SPF setup might not be enough to prevent Outlook's warnings.This highlights a common point of confusion for marketers: the exact level of detail required in SPF records when using third-party ESPs.
What the experts say
Email experts consistently emphasize that phishing warnings on emails sent via third-party ESPs like SendGrid from a CRM are primarily an authentication and alignment issue, not necessarily a sign of a true security breach if configured correctly. Their insights revolve around the technical intricacies of how email providers, especially Microsoft, validate the authenticity of incoming messages.Experts stress the critical role of domain alignment, particularly with DMARC, and highlight that merely passing SPF or DKIM may not be enough if the authenticated domain doesn't match the human-readable 'From' address. They advocate for complete control over sending domain identity to mitigate these warnings and ensure legitimate emails are not mistaken for phishing attempts.
Key opinions
- Admin Control: The rule for displaying such a header is often set by the O365 administrator, with various possible criteria. It's not necessarily a default change by Microsoft, but rather an activated policy.
- BEC Spam Indication: Such warnings are typical for Business Email Compromise (BEC) spam, where external entities try to impersonate internal senders.
- Authentication Gaps: The issue could stem from problematic authentication, or simply from unknown or undeclared IP addresses that are sending mail on behalf of the domain.
- DKIM Domain Alignment: If emails authenticate as SendGrid's domain (e.g., d=sendgrid.net), but appear to be from your organization, the warning is legitimate. The solution is to sign with your own domain in DKIM (d=yourdomain.com).
Key considerations
- Comprehensive Authentication: Beyond just SPF, ensure DKIM is fully configured to use your own domain and that a DMARC policy is in place. This simple guide to DMARC, SPF, and DKIM explains the relationship.
- Custom DKIM Domain: Prioritize configuring SendGrid's custom domain setup for DKIM. This is often the most direct path to resolving these specific Outlook warnings, as it ensures DKIM alignment with your From domain.
- Review Microsoft Policies: Microsoft's anti-spoofing protection is sophisticated. Understand how your O365 environment is configured and check for any specific spoof intelligence policies that might be impacting your legitimate emails. Information on how to comply with Outlook's new sender requirements can be helpful.
- Regular DMARC Monitoring: Utilize DMARC reporting to gain visibility into your email streams and identify authentication failures. This data is crucial for diagnosing and fixing issues that lead to phishing warnings. You should also be aware of specific DMARC reports from Google and Yahoo as they provide valuable insights.
Expert view
Expert from Email Geeks suggests that a phishing warning occurs when an email authenticates (via SPF or DKIM) as SendGrid, but the sender appears to be from your own organization. They confirm that this warning is legitimate as it signals a potential spoofing attempt.The expert advises that having this warning in place is beneficial, as it protects against actual malicious senders trying to impersonate internal employees.
Expert view
Expert from Email Geeks strongly recommends signing emails with your own domain's DKIM ("d=") in SendGrid. This ensures that the email's authentication aligns with your organization's domain, making the warning disappear.They consider this a minimum requirement to prevent legitimate internal-looking emails from being flagged as suspicious, emphasizing that proper DKIM alignment is paramount.
What the documentation says
Official documentation from email service providers and security entities consistently outlines the technical standards and best practices for email authentication. These documents provide the definitive rules by which emails are validated, and how issues like phishing warnings are triggered. They emphasize the importance of SPF, DKIM, and DMARC for proving sender identity and preventing spoofing, which is the underlying concern behind Outlook's phishing warnings.The documentation typically details how to correctly configure DNS records to authorize third-party sending services and highlights the specific conditions under which receiving mail servers, such as those operated by Microsoft, will flag an email as suspicious. Adhering to these documented standards is crucial for ensuring email deliverability and avoiding security alerts.
Key findings
- SPF Failure Detection: Documentation indicates that an SPF failure means the receiving server (like Outlook) could not verify that the sending server is authorized by the domain owner. This is a direct trigger for security warnings.
- DNS Record Updates: It is consistently stated that SPF records in DNS must include all services authorized to send emails on behalf of a domain. Missing inclusions lead to authentication failures.
- DKIM and DMARC Necessity: Official guides often stipulate that adequate configuration of DKIM, SPF, and DMARC records for the sender domain is mandatory for proper authentication and to avoid spam or bounce issues.
- Phishing Reporting: Outlook's ability to report an email as phishing is enabled by default, and Office 365 administrators can add custom rules to enhance this detection.
Key considerations
- Sender Address Verification: Documentation for email services frequently advises checking the sender's email address for authenticity, indicating that strange or unfamiliar addresses are red flags for phishing attempts.
- Mailer Service Connection: Guides on email delivery issues, particularly for CRMs, often recommend connecting to a dedicated mailer service (like SendGrid via SMTP) and properly authenticating the domain with that service.
- Native Integrations: Some documentation suggests that using native integrations between a CRM (or WordPress) and an ESP (e.g., Fluent SMTP with SendGrid) can resolve email delivery issues by ensuring proper communication and authentication.
- DMARC Policy Enforcement: Documentation on DMARC highlights its role in defining how receiving servers should handle emails that fail SPF or DKIM alignment. A strong DMARC policy helps enforce sender authenticity and reduce spoofing. Our article on 'Messages can be spoofed' warnings in Outlook delves into this topic.
Technical article
Documentation from Digital Marketing on Cloud explains that an SPF failure specifically means Outlook could not verify that the sending server is authorized by your domain. This directly contributes to emails being flagged as suspicious or unverified.It strongly advises updating your DNS SPF record to explicitly include all services, like SendGrid, that are permitted to send emails on your behalf to prevent such authentication failures.
Technical article
Documentation from MailBluster emphasizes that adequate configuration of DKIM, SPF, and DMARC records for your sender domain is crucial for deliverability. It clarifies that merely verifying the sender's email address is insufficient to ensure proper authentication.This highlights the need for domain-level authentication rather than simple email address verification to prevent emails from being marked as spam or generating warnings.
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