SMTP Email / WordPress Issue

Looking for a email SMTP expert for the following task.

Setup
- WordPress website running on a AWS LightSails instance
- Emails routed and going through SendInBlue SaaS platform

Issue
- Emails are not coming out of the site when uses sign up, place an order etc.

Task
- You need to fix the email sending issue
- You need to fix any routing issues coming from AWS to SendInBlue
- You need to test all email functions that they work