Why just an excerpt in the email?

Although I do want to drive traffic to my site, that's not the reason for this decision. It's based on my own experience with email newsletters, having subscribed to a lot of them over the last five years. I have found that an email with a long, or even medium-length, post has a kind of "weight" to it, and this weight is, if not a physical burden, then a psychic one. I think the problem is there's a conflict here between what a good newsletter wants (to be a meaty read) and what an email wants (to be read and thrown away immediately). What ends up happening is that I read some, others I delete without looking, and some end up just sitting there, unread and undeleted. These unread newsletters generate guilt from being unread but I always tell myself "I'm going to read it, I'm going to read it." Do I? Only sometimes. 

Here's the stupid part. That same newsletter post? When it's in a browser tab, it weighs nothing. A single unread email feels like a boulder on my back, but I can have a million tabs open and feel light as a feather. What's more, if I have the newsletter open in a tab, I end up reading it within a day, maybe two at most. 

I don't understand this dynamic, why it happens, but I know, for me at least, it's real. And if it's real for me, I'm certain it's real for others. That's why I've decided that my newsletter will be written so that it can be read quickly, then deleted. If there's something interesting in it, I trust readers to click on it and get it on their browser to read. But I don't want to clog up your email with long posts that feel like a burden.