Your campaigns are being filtered to the Promotions tab in Gmail
Internally, you can change your Gmail settings to "Not Promotions." Here is a link to help from google support: https://support.google.com/mail/answer/3094499?hl=en&ref_topic=3394594&rd=1
Externally, whether or not your campaign lands in the Promotions or Primary tab in Gmail is going to depend on the recipient's actions. There's a few things that could help:
- If your subscribers move your campaigns from the Promotions to Primary tab, that will help them land in Primary for the next time!
- If your subscribers add your From address to their Google contacts, your campaign should land in their Primary.
Overall, make sure that you're maintaining a healthy, engaged subscriber list and sending relevant content. That will increase your chances of landing in the Primary tab.