Slack, Asana, and Dossier all have free editions of their products. Very soon, you will reach the limitations that the free editions have, but it will be long enough for you to try the techniques above. G Suite and Office 365 are not free apps, and you will pay approximately $5/mo for each email account. Here is where you can download and sign up for these apps:
In summary, you can share Gmail or Outlook accounts to setup a single mailbox and have your team members share these accounts. Alternatively, you can manage these emails in Dossier, Slack or Asana where you can collaborate with your team more efficiently to review and respond to customer inquiries. Let’s get to a better place with managing incoming emails!