Adding headers to a TMail object

I get a header that is set on a TMail object using

my_mail[“my-header”]

but I can’t seem to figure out from the docs how to add headers.

Can anyone show me an example of how to set the header “my-header” to
“my-value”, please?

Mark

Bleh, ignore this.

It is as simple as my_mail[“my-header”] = “my-value”

Duff code in my tests was hiding the real problem!

Mark