Does gmail preserve x-headers in email replies?
I’m developing an application which threads emails and email replies together using a Thread Id.
I add the header through SMTP .net library with the thread id, using the key X-ThreadId.
If I send it to a gmail account, I can see the header in there in the email source. However if I then reply to it, I want that header to be sent in the reply. It seems to drop that particular header.
Does gmail drop header information in the reply email? Is this a generic problem with email? If so, how do I get round this problem?
I can confirm that Gmail does not add X- headers to the new email when you hit reply button.