HTTP::respond - bug or improper use?

Interesting.

I replicated what you have as closely as possible and can only suggest that you set the values to a known state and string tolower your values. This is a sample of what I tested and it worked, so there is some other detail that I am missing from being able to replicate your issue.

when HTTP_RESPONSE {
if { [string tolower [HTTP::header exists "server" ]] } {
switch [string tolower [HTTP::header value "server" ]] { 
"microsoft-iis/6.0" { HTTP::respond 302 Location "https://www.google.com" }
}
}
}