speckle-server/packages/server/assets/emails/templates/components/headerLogo.mjml

<mj-section padding-bottom="0">
  <mj-column>
    <mj-image
      width="40px"
      src="<%- params.serverInfo.canonicalUrl -%>/static/speckle-email-logo.png?v=1"
      alt="Speckle"
    />
  </mj-column>
</mj-section>