You can check if anybody has unsubscribed or if your emails have bounced from your Campaigns page. To see the number of unsubscribed or bounced for each campaign, click on the '...' drop-down menu next to 'Actions' and select 'Outreach Status'. This will display a pop-up indicating the number of unsubscribed and bounced emails.
You can also view the Bounce Log for each email address associated with your Pitchbox account. Click 'Settings' on the top-nav bar and select 'Email Accounts'. On the Email Accounts page click 'Deliverability' and select 'Bounce Log'. Here you will be provided an overview of your Last 100 Outreach Email Bounces and the option to download all bounces.