Unauthenticated SMTP to localhost on port 25 without STARTTLS doesn't work

@kate it appears that this role no longer configures Exim4 to allow unauthenticated SMTP to localhost on port 25 without STARTTLS?

For example:

ssh wsh.webarchitects.org.uk
sudo -i
su - wiki
mutt

Try to send an email and it fails with:

SMTP session failed: 454 TLS currently unavailable  

This is with the following ~/.muttrc

set tmpdir="~/tmp"
set folder="~/.mutt"
set record="+sent"
set smtp_url=smtp://localhost:25/
set ssl_starttls=no
set hostname="wsh.webarchitects.org.uk"

Have you any idea what config changes are needed to either set Exim4 to use the Let's Encrypt key and cert the server has or to enable connections from localhost to not require STARTTLS once more? I'm sure this did work in the past.