Why is Outlook displaying phishing warnings on emails sent from my CRM through Sendgrid, and how can I fix it?
Summary
What email marketers say7Marketer opinions
Email marketer from Reddit shares that implementing DKIM signing is crucial. By signing emails with a DKIM signature linked to your domain, you verify the email's authenticity and prevent it from being flagged as phishing.
Email marketer from EmailGeeks Forum explains that setting up DKIM with your own domain (d=yourdomain.com) ensures that the email is signed by your organization, even when sent through Sendgrid, reducing the likelihood of phishing flags.
Email marketer from Sendgrid details that if your CRM sends emails on behalf of your domain through Sendgrid, ensure Sendgrid's servers are included in your domain's SPF record. An incomplete SPF record is a common cause for emails failing authentication.
Email marketer from Stack Overflow shares that using a dedicated IP address for sending emails from your CRM helps build a positive sending reputation, which reduces the chances of emails being marked as phishing.
Email marketer from Mailhardener shares that authentication is not optional, they recommend implementing SPF, DKIM and DMARC.
Email marketer from EasyDMARC describes some of the common reasons for poor email deliverability. They include SPF, DKIM and DMARC configuration issues.
Email marketer from DNSQueries explains that regularly monitoring your domain's reputation and IP address on blocklists helps identify and address any issues that might cause emails to be flagged as phishing.
What the experts say3Expert opinions
Expert from WtotheWise details that authentication is required, this requires that you are using SPF, DKIM, and DMARC records, and that they are aligned.
Expert from Spamresource explains that internal spoofing prevention is a frequent problem with hosted services. Ensure SPF records cover all sending sources and consider a DMARC policy to reject unauthenticated mail.
Expert from Email Geeks explains that if email is authenticating (DKIM or SPF) as Sendgrid, then it’s going to look like phishing and the warning is legit. She suggests signing with your own d= in the DKIM to see if that makes the warning go away.
What the documentation says4Technical articles
Documentation from Microsoft Learn explains that Outlook flags internal emails as phishing due to spoofing. If an email claims to be from an internal sender but fails authentication checks (SPF, DKIM, DMARC), Outlook may flag it as suspicious.
Documentation from Microsoft indicates that the Sender Policy Framework (SPF) is an email-authentication method designed to detect forging sender addresses during the delivery of email.
Documentation from DMARC.org explains DMARC policy. A DMARC policy tells receiving mail servers how to handle emails that fail SPF and DKIM checks, helping to prevent spoofing and phishing.
Documentation from RFC explains that the SPF record should include all authorized sending sources, including Sendgrid's IPs or domain. Failure to include all sources will cause emails to fail SPF checks, leading to potential phishing warnings.