Including a carefully edited selection (up to 3) of low-res images in the email with your media or product release is a great idea.
It gives the editor or reporter a sense of your style, your brand, and how your image could look on a page in their publication.
It also means that if they are short on photographers they can run your story using your images, rather than binning it because they can't get a photographer to you.
Just make sure that the images you send suit the publication. If it's a newspaper, you want news-style shots: casual portraits, nothing too processed, true colours (no washes, fades or amped up colours), and interesting images showing activity or movement.
If it's a glossy mag, you might go for more of a high-end lifestyle shot, or a pure product shot that can be deep-etched, for example.
If they like your images, they will ask you to send high-res versions through. This is almost always a very good sign they're going to use your lovely creations.