"Those options that undergo string expansion before use are marked with †."
Thanks! It's always the fine print that gets you :) After further investigation (thanks -d+expand!), I must retract my earlier statement about my readfile assignment not causing any issues. It was :) ╭considering: $primary_hostname ├──expanding: $primary_hostname ╰─────result: ${readfile{/etc/mailname}{}} ... SMTP>> EHLO ${readfile{/etc/mailname}{}} For posterity, going back to my original post, TLS certificate options *are expanded* and can indeed be dynamic! This works just fine... not that it's the most efficient way :) tls_certificate = /etc/letsencrypt/live/${readfile{/etc/mailname}{}}/fullchain.pem Thanks Jeremy for the help! Lance -- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/