Email Signature for Thunderbird

An email signature for Mozilla Thunderbird is configured per-account in Account Settings > [Account Name] > [Identity], where the user enters signature text directly or attaches an external HTML or text file. Thunderbird supports rich HTML signatures and is more permissive of complex HTML and CSS than Outlook desktop, since Thunderbird uses Mozilla's Gecko rendering engine rather than Microsoft Word's. Organizations deploying Thunderbird at scale typically use the autoconfig or policy file mechanism: a centralized configuration file (`autoconfig.cfg` or `policies.json`) on each user's machine pre-sets the signature path or content. For Microsoft 365 or Google Workspace mailboxes accessed via Thunderbird, server-side stamping at the mail server is the most reliable centralized approach because it applies regardless of which client the user composes from. Thunderbird's signature implementation lacks the directory-sync depth of dedicated signature management platforms; for organizational deployments, signature management software with server-side stamping is preferred over per-client configuration.