In a shared IMAP environment, the identity designation (e.g., id2) for a given identity can vary from client to client. The X-Identity-Key header that Thunderbird adds to templates is used by clients to designate the identity from which the template-based message is sent. If id2 (in this example) varies from client to client, then sending of the message from the intended identity cannot be guaranteed.

A workaround is to manually delete the X-Identity-Key header from the template, but with many and changing templates, this is impractical. Is there an option to suppress (or ignore) the X-Identity-Key header?