VerifySeal ManagerLive verification platform
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Install an Email Sender Seal in Thunderbird signature

Create an HTML signature for the verified sender and insert the linked Email Sender Seal image.

TB
Recommended methodEmail-signature linked image
Email-signature installation

Step-by-step instructions

  1. 1

    Create an HTML signature file

    Create a small HTML file containing the Basic linked-image embed supplied by VerifySeal. Keep the target, rel, image source, width, height and certificate link unchanged.

  2. 2

    Assign it to the sender account

    In Thunderbird Account Settings select the verified email account, enable Attach the signature from a file instead and choose the saved HTML signature file.

  3. 3

    Compose in HTML

    Start a new formatted message from the verified sender address and confirm the seal appears at the expected size. Plain-text messages cannot display the seal image.

  4. 4

    Send an external test

    Send to an external mailbox, display remote images if required and click the seal to confirm it opens the live Email Sender Verification certificate.

Open Thunderbird signature documentation ↗
Email Sender Verification Seal

The signature image is only one part of verification

The sender domain must continue to publish a valid SPF record, the selected DKIM key and a DMARC policy. VerifySeal automatically rechecks these records according to the administrator schedule. For High Security messages, DKIM must cover the final Message-ID, VEM header and completed body.

  • SPF authorizes sending services
  • DKIM verifies the signed message domain
  • DMARC publishes the domain policy
Testing checklist

Confirm the installation is working

01

Visible

The complete 300 × 106 seal is visible in a received HTML message and is not cropped.

02

Clickable

The image opens the live VerifySeal sender certificate rather than an unlinked copied image.

03

Correct sender

The signature is assigned to the exact verified From address, not another identity or shared mailbox.

04

External test

A message received outside the organization retains the image, hyperlink and passing authentication results.

Platform notes
  • If a security policy blocks remote images, recipients can still use a linked text fallback placed beside the seal.
All seal types

View every available VerifySeal design

Domain OwnershipEmail Sender VerificationHigh Security Email VerificationVerified BusinessVerified OrganizationVerified ResellerTrusted WebsiteCertified MemberAustralian Builder LicenceAustralian Financial Services LicenceWebsite PCI DSS ComplianceDocument IntegrityVerified Issuer DocumentHigh Security Document Authentication