Why can't I send png file visible in email body?

I did this many times, and it worked.

Now i created a task.

In attachment I added “C:\Users\botcreator1\Desktop\invoiceKumulatifKontrol.png”

and in email body, 

<img src="cid:invoiceKumulatifKontrol.png">

but it sends it in attachment. What should I do?