Email Deliverability is something you must monitor when sending cold emails.
Here are a couple of quick tools you should use to make sure your emails hit the inbox.
1. Check the number of emails you have authorised PPC Ad Lab to send for each SMTP.
2. Check Your Email sending using https://www.mailgenius.com/ and make the adjustments they recommend.
Remember deliverability is something you should be monitored regularly and is controlled by your management of your SMTP, not PPC Ad Lab.