Need cPanel/WHM Email Delivery Expert – Emails Sending but Not Delivered

We're looking for an experienced cPanel/WHM expert to diagnose and solve a critical email delivery issue.
Our emails are sending successfully (no error returned), but not being delivered to the recipients' inboxes or spam folders.

Requirements:
Strong experience with cPanel & WHM (latest version)

Deep knowledge of email configuration, DNS records (SPF, DKIM, DMARC)

Ability to analyze mail logs, queue issues, and blacklist problems

Ability to troubleshoot issues with Exim, MailScanner, or 3rd-party SMTP relays

Bonus: Experience with Mail Delivery Reports, SpamExperts, or CSF/LFD

Goal:
Identify the root cause of the delivery failure

Fix the issue and ensure emails are delivered reliably

Provide a short report on the issue and solution

Please only apply if you have direct experience with similar issues and can work via SSH/WHM or screen share.