What causes the Gmail authentication alert and how to resolve it?

Email marketer from StackOverflow mentioned that a missing DKIM signature can also trigger the 'sender is unauthenticated' warning. The user suggests confirming that the DKIM signing process is correctly implemented on the sending server.

Email marketer from Mailjet explains that the 'sender is unauthenticated' warning in Gmail means your emails might not be passing SPF or DKIM checks. To fix this, ensure you've properly configured SPF and DKIM records for your sending domain and that they are validated.

Email marketer from Email Marketing Forum mentions to ensure your SPF record includes your ESP's servers if you are using one. They found that forgetting to add their ESP to the SPF record was causing authentication issues.

Email marketer from Reddit shares their experience that an invalid SPF record caused the authentication error. They suggest double-checking the SPF record syntax and ensuring it includes all sending sources.

Email marketer from Gmass explains that it usually means one of the email authentication methods hasn’t been correctly set up and Gmail can't verify the message is legitimate. Authenticating your emails is vital to prevent spam classifications. This can be achieved via SPF, DKIM and DMARC

Email marketer from SparkPost explains that if authentication checks fail, a recipient server can’t confidently confirm the message’s origin, resulting in spam classifications or messages being blocked outright. You need SPF, DKIM and DMARC.

Email marketer from Email Geeks shares that they resolved the issue by identifying that the domain's aspf and adkim were set to strict.

Email marketer from EasyDMARC explains that Gmail showing 'sender is unauthenticated' means your emails aren't passing authentication checks. Implement SPF, DKIM and DMARC properly. Validate the records using online tools and adjust your DMARC policy gradually.

Email marketer from Sendinblue responds that setting up SPF, DKIM, and DMARC, will prove to mailbox providers that you are who you say you are. If these records are not set up properly, your emails can easily end up in spam folders.

Expert from Word to the Wise, Laura Atkins, answers that the 'unauthenticated sender' notification isn't necessarily about deliverability but about helping Gmail users identify legitimate senders. She explains that ensuring proper SPF and DKIM setup helps associate your branding with your emails and build trust with Gmail recipients, preventing the alert.

Expert from Email Geeks explains that the Gmail alert likely means the email is not aligned authenticated and suggests checking the auth-results header.

Expert from Spam Resource explains that the 'Gmail sender unauthenticated' alert often arises from missing or misconfigured authentication records, specifically SPF and DKIM. The primary cause is often failing alignment checks between the 'Header From' domain and the domain used for SPF and DKIM authentication. Resolution involves ensuring that the SPF record accurately lists all authorized sending sources and that DKIM signatures are valid and correctly aligned.

Documentation from Microsoft responds that they have been using email authentication for over a decade to verify the sender of an email message isn't forged, and that the source IP address of the sending server is authorized to send mail for the sending domain.

Documentation from Google Workspace Admin Help explains that a 'sender is unauthenticated' message typically occurs when a message fails SPF or DKIM checks. Resolving this involves ensuring proper SPF, DKIM, and DMARC setup.

Documentation from RFC explains that Sender Policy Framework (SPF) is an email authentication method designed to detect forging sender addresses during the delivery of email. Specifically, SPF prevents spammers from sending messages with forged 'from' addresses at your domain by publishing DNS records.

Documentation from DMARC.org explains that Domain-based Message Authentication, Reporting & Conformance (DMARC) is an email authentication protocol. It is designed to give email domain owners the ability to protect their domain from unauthorized use, commonly known as email spoofing.

Documentation from RFC explains that DomainKeys Identified Mail (DKIM) lets an organization take responsibility for a message by associating a domain name with it, digitally signing it. Message recipients can verify the signature by querying the signer's domain, thus confirming the message's authenticity.