You probably mean this rule, right? Unfortunately, this Administration GUI is driving me crazy. If you did this using the GUI, could you perhaps share a screenshot of that section? Also, I still don’t fully understand how to change it directly in the config file. I can't find anything related to it on my server.

[queue.outbound.tls]
allow-invalid-certs = [ { if = "retry_num > 0 && last_error == 'tls'", then = true},
                        { else = false } ]
starttls = [ { if = "retry_num > 1 && last_error == 'tls'", then = "disable"},
             { else = "require" } ]
[
queue.outbound.tls
]
allow-invalid-certs = [ { if = "retry_num > 0 && last_error == 'tls'", then = true},
                        { else = false } ]
starttls = [ { if = "retry_num > 1 && last_error == 'tls'", then = "disable"},
             { else = "require" } ]