Send newsletters without the whole post

I have a single free membership tier on my website, which allows access to all posts without any cost. Currently, when I publish a new post, all subscribers receive a newsletter containing all the new page content. However, I would prefer that they visit my website and access only a portion of it from the newsletter, thereby reducing its size. The newsletters sent from ghost are approximately 150 kb, whereas other companies’ emails in my inbox are typically around 10-50 kb top. This issue has become burdensome as users receive large emails and fail to visit the website.

How can I address this problem?