A press release is simply an announcement of a newsworthy event, information that is timely, entertaining, interesting, or helpful. A punchy headline is critical in getting your press release noticed. Releases can be distributed by email, snail mail, or fax. Do not use attachments with a press release. Most editors will delete the entire email unopened because of the potential of viruses in unsolicited attachments.
Don't send the press release as a PDF file. PDF files can't be copied and pasted if the recipient doesn't have the correct Adobe program. This means the editor will have to have the entire release re-typed and they probably won't do it.
The release can go on your corporate stationary and include a photo of the product if relevant. It can also, of course, be emailed.