Senior Systems Engineer

Mission Inbox; United States; Remote; USD 120,000 - 160,000; Full time

Job summary

Mission Inbox Inc. is seeking a seasoned Linux Systems Administrator/DevOps to manage high-scale mail infrastructure.

You will tune Postfix, Dovecot, and Postal, implement spam filtering with Rspamd, and harden security with Fail2Ban while overseeing HAProxy, FRRouting, and PostgreSQL replication. You will own DNS and authentication protocols (SPF, DKIM, DMARC, BIMI), automate IP warm-ups, and build robust log pipelines with Vector.

Qualifications

• 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.

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.

Skills

Linux systems administration

Mail server administration

Network routing and load balancing

DNS and DMARC expertise

Security hardening

Traffic throttling and deferral relief

Tools

Postfix

Dovecot

Postal

HAProxy

FRRouting

PostgreSQL

Rspamd

Fail2Ban

Vector

Job description

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.