I would like to Include a single line in the email subject that indicates the NPS rating that user has responded to the question. is this possible and how can i do? i am using LimeSurvey 1.87 version.

Hi, vama,
this is no problem with Expression Manager.
See (example in version 2.06):


The problem might be your ancient version. LS 1.87 was launched 10 years ago.
And as far as I know, Expression Manager was implemented in version 1.92.

So the advice is to update, at least to version 2.06, which has the same look and feel as 1.87

You find this version here:
www.limesurvey.org/stable-release/category/24-archived-releases

You might be able to work with the SGQA codes, but you really, really, really should consider an upgrade. Your version of LS hasn't received security batches and updates for many years now. It is not recommendable to use such an old version of LS. And not only because of security, there have been many improvements since 1.87. LS is free, you don't have to pay licence fees. I don't get why people wouldn't update for such a long time.