Before sending your Press Releases, if you'd like to check if any Journalists have unsubscribed from your Groups, you can do so from the Distributions area.

You can then create your Distribution as usual by clicking Compose Distribution at top right, click the Distribution Channels tab as per the below and from there select Email.

Click the Plus button under Contacts. The filters at the top of the window will then allow you to look up the unsubscribed contacts.