How Email Authentication Influences Consumer Trust and Email Deliverability

As most marketers know, trust is paramount when it comes to email marketing success.

According to Fastmap, three out of five consumers across every age group rate trust as the number one influencer that persuades them to share personal data–such as primary email addresses–with companies.

And primary email addresses are the foundation upon which email marketing ROI depends. More than 80% of responses generated by a typical email program are from primary email addresses, which means (in theory) that over 80% of the revenue generated by a typical email campaign depend on primary email addresses, too.



So what does trust have to do with email authentication?
Gmail recently made some important changes to the way it processes inbound emails—and these changes may have a big impact on consumer trust.

In case you missed it, here are the highlights:

  • For users who receive an email from a sender that did not encrypt the message using Transport Layer Security (TLS) encryption, Gmail will display a broken lock icon in the message.

  • Users who receive an email that can’t be authenticated with either Sender Policy Framework (SPF) or DomainKeys Identified Mail (DKIM) will see the sender’s profile photo or avatar replaced with a red question mark.

We’ve now started to see some real-world examples of this:



Gmail isn’t the only internet service provider starting to warn end-users about unauthenticated email. Microsoft will soon follow suit (and we predict others will too) redacting logos and graphics and adding red indicators if an email lacks proper authentication.

When consumers see an email with a question mark or broken lock in place of a logo, they will not only be less likely to engage with that email but will also be less likely to engage with that brand.

A decline in trust leads to a decline in deliverability
Poor engagement leads to a sharp decline in performance. Gmail places great importance on signals of positive and negative subscriber engagement in the inbox and uses them to inform filtering decisions. These signals include:

  • Emails read
  • Emails deleted without reading
  • Spam complaints
  • “This is not spam” notifications
  • Email replies
  • Emails that are “starred”

Such metrics combine to provide an overall view of subscriber sentiment. If subscriber sentiment declines, so will inbox placement rates at Gmail, and with a reduced deliverability comes reduced revenue.

Consider the following scenario:

  • List of one million email addresses
  • One-third of these are Gmail inboxes
  • Sending frequency: twice per week
  • Average value $0.08 per email

A reduction of just one percent in inbox placement rate at Gmail from erosion of trust, would represent an opportunity cost to the sender of $230K per year.

What should senders do if their emails are failing on authentication?
To avoid the pitfalls of unauthenticated legitimate messages, senders should prioritize Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and DMARC (Domain-based Message Authentication Reporting and Conformance) implementation.

DMARC leverages both SPF and DKIM and represents the first step in generating visibility into email fraud threats. It empowers senders to work directly with mailbox providers to quarantine or reject any email that fails authentication.

Eliminating these threats reinforces trust between a company and its customers, which drives up engagement and maximizes program ROI. Return Path helps some of the world’s top businesses do this through, optimizing email authentication to improve deliverability and identify malicious activity targeting their brand and sending domains.

To get started with DMARC implementation at your company, download our step-by-step guide, “Getting Started with DMARC.

minute read

Popular stories



BriteVerify email verification ensures that an email address actually exists in real-time


The #1 global data quality tool used by thousands of Salesforce admins


Insights and deliverability guidance from the only all-in-one email marketing solution

GridBuddy Cloud

Transform how you interact with your data through the versatility of grids.

Return Path

World-class deliverability applications to optimize email marketing programs

Trust Assessments

A revolutionary new solution for assessing Salesforce data quality


Validity for Email

Increase inbox placement and maximize subscriber reach with clean and actionable data

Validity for Data Management

Simplify data management with solutions that improve data quality and increase CRM adoption

Validity for Sales Productivity

Give your sales team back hours per day with tools designed to increase productivity and mitigate pipeline risks in real-time