We are trying to implement one click unsubscribe as per https://support.google.com/a/answer/81126?hl=en#subscriptions&zippy=%2Crequirements-for-sending-or-more-messages-per-day
I used the below code to add headers but its seems they are not being added
#set($options = "%{}")
$options.Add("List-Unsubscribe","<https://abcd.com/unsubscribe?token=abc123>")
$options.Add("List-Unsubscribe-Post","List-Unsubscribe=One-Click")
$core_v2_email.Send("testunsubscribe4", "testbody4", "%{ ToEmail='xxxx@gmail.com' ,Headers = $options }")