How to make newsletter show up with it's post title instead the blog name?

When I set up my newsletter and test it out. I found there was the title of the blog name shows up from my email subject field. For example my site is “birth of a fashion line”, and I write a new post like “4 majoy silk market in china” or “how much a retail space cost” I need both of the post name to show up in the email subject field to attract reader’s attention, instead the same “birth of a fashion line” show up every time.

Can anyone tell me how to make the newsletter show up with its’ post title instead the blog name?

Thank you