Can anyone help to remove the token like CRM:XXXX000 from subject line of email generated through plugin code ?
CRM 2011 had some settings to remove this but in CRM 2016 I am not getting that setting.
Am I missing something or CRM2016 does not allow it ?
That is the tracking token which alows CRM to (as the name implies) keep track of the emails.
To remove the tracking token go to Settings > Administration > System settings > Tab Email and uncheck "Use Tracking Token"