I think the source of the annoyance for Andrew’s community members is %{header_instructions}.
That token expands to a fairly large block of boilerplate (“do not reply…”, links, instructions, etc.) and it appears at the very top of the email body in many notification templates. For experienced users it dominates the message and reads as nagging rather than helpful.
There’s currently no site-wide setting to disable or relocate it. To remove it, an admin has to edit every email template individually under Admin → Email → Templates.
On current latest-release (I’m on latest-release +17), it should be possible to address this centrally with a Rails script for templates that already have DB overrides, e.g. stripping %{header_instructions} when it appears at the start of the body. That part is straightforward and uses the EmailTemplate model.
Applying the same change to all stock templates (including those without existing overrides) would require creating overrides by pulling in the default template bodies via internal lookup APIs. That’s feasible, but it depends on Discourse internals and would need a maintainer to review/validate before being recommended broadly.
So the underlying issue isn’t just the content of %{header_instructions}, but that it’s effectively global boilerplate with no admin-level toggle, and removing or moving it requires per-template manual work or unsupported scripting.