Senior Systems Engineer

Responsibilities

• Maintain and configure core MTAs (Postfix, Postal) and IMAP/POP3 servers (Dovecot)
• Utilize HAProxy and network routing protocols like BGP via FRRouting for traffic distribution
• Administer backend infrastructure databases including PostgreSQL replica setups
• Act as technical authority on DNS and authentication protocols including SPF, DKIM, DMARC, and BIMI
• Implement automated MTA-level dynamic throttling to handle 4xx deferrals
• Design and guide automated IP/Domain Warm-up Plans
• Configure and optimize Rspamd for outbound spam filtering
• Deploy automated connection-dropping systems like Fail2Ban to mitigate attacks
• Build and manage high-performance log aggregation pipelines using Vector
• Monitor ISP infrastructure portals including Google Postmaster Tools and Microsoft SNDS

Requirements

• 5+ years of experience as a Linux Systems Administrator, DevOps, or Infrastructure Engineer
• Expert-level proficiency with Postfix, Dovecot, or Postal
• Hands-on experience with Rspamd and Fail2Ban
• Proven experience building log pipelines using Vector or similar frameworks
• Experience with HAProxy, FRRouting, and PostgreSQL replication
• Deep understanding of TCP/IP, routing, ports, and DNS management
• Expert parsing of aggregate DMARC reports

About the Company

Mission Inbox is focused on high-scale email infrastructure and deliverability services.