[exim] Problem with tls_certificate and multiple domains

After many hours of troubleshooting, I cannot figure out how to correctly setup tls_certificate for multiple domains. I’m using CentOS 7.7 and Exim 4.92. I have only one exim.conf file. I have in the main body:

tls_certificate = /etc/exim/private/certs/${lc:${domain:$h_from:}}/cert.pem
tls_privatekey = /etc/exim/private/certs/${lc:${domain:$h_from:}}/privkey.pem

The expansion results in blank.

I’ve also tried $tls_in_sni and $tls_sni which also return blank. (Using Apple Mail on Mojave as a client).

When I use exim -bem <test.msg> '${lc:${domain:$h_from:}}’ I get the domain back as expected.

Most of the examples refer to many other config files in different OS flavors so have attempted to work them into the exim.conf and have tried several things including:

##########################

begin transports

remote_smtp:
    tls_certificate = /etc/exim/private/certs/${lc:${domain:$h_from:}}/cert.pem
    tls_privatekey = /etc/exim/private/certs/${lc:${domain:$h_from:}}/privkey.pem

##########################

The above doesn’t seem to be recognized even with remarking out the main body tls_certificate and tls_privatekey.

I also tried sender_address_domain but that contains the root user.

What is the appropriate variable to use for retrieving the senders domain?

Thanks,
Davf