Gmail / yahoo threading email including attachment

Is there a way to force gmail / yahoo in threading emails with the same subject?

Here's what happened with the email that i sent.

Yahoo - the second email is combined with the first email 开发者_如何学JAVAincluding the attachment.

Gmail - The second email is empty and no attachment. The body was replaced with "Important mainly because of the people in the conversation."

I am not sure if threading is causing this problem. is there any way to fix this?

Yahoo and Gmail detect if the e-mail is in the same context. So a similar body, and same subject.

if you make an e-mail more specific (different contents) it should not make it a thread.

But Threading should not cause the loosing attachment problem. You should dig deeper on that, by looking to your own code.

It is not possible that your contents go away just like that. In Gmail you can disable threaded view in settings, and I am not sure about yahoo, but it should have options for that