Email Deliverability and Infrastructure Expert for Mass Mailing Platform Re-architecture

We are seeking an expert in email deliverability and mail infrastructure (MailOps/DevOps) to help us re-architect the mass email sending architecture of our platform. We need a professional with proven experience to enhance our email deliverability and reputation management.

Current Context:
We operate our own platform for managing lists and sending mass emails, based on Mailman 3. Email sending is currently routed through an external server using rotatable virtual IPs. The system employs a 'controlled spoofing' model where the 'From:' address belongs to the client, but all spf/dkim/dmarc authentication is handled by us. This current setup limits deliverability, especially with domains enforcing strict dmarc policies, and places all ip/domain reputation responsibility on us.

What We Need:
We require a redesign of our architecture to align with leading providers such as Mailchimp, Sendgrid, and Brevo. Key objectives include:
- Establishing a dedicated domain/subdomain for authentication (e.g., Mail.nekotechnologies.com).
- Implementing custom mail from and return-path controlled by us.
- Setting up IP pools and subdomains for reputation segmentation.
- Developing robust tracking for bounces and complaints.
- Maintaining list management with Mailman 3, but integrating it with a modern MTA (optimized Postfix, PowerMTA, or Postal).
- Comprehensive documentation of the entire architecture and configuration to enable our internal team to manage it effectively post-implementation.

Project Timeline (Estimated 4 Weeks):
- Week 1: Domain and dns setup, mta deployment, and basic testing.
- Week 2: Mailman ↔ MTA integration and bounce tracking implementation.
- Week 3: IP pools configuration, warm-up procedures, and testing with major ISPs.
- Week 4: Monitoring setup, alert systems, and final documentation.

Profile We Are Looking For:
- Demonstrable experience in email deliverability and MTA configuration (Postfix, PowerMTA, Postal).
- Deep knowledge of spf, dkim, dmarc protocols, feedback loops, and ip warm-up strategies.
- Ability to define, deploy, and clearly document complex technical architectures.
- Experience in monitoring and managing email reputation (IPs, queues, blocklists, ISP policies).
- A freelance/consultant profile available for an intensive implementation phase and subsequent ad-hoc support.