Senior Systems Engineer - Email Deliverability & Infrastructure

Stack

Responsibilities

• ▹Maintain and configure core MTAs (Postfix, Postal) and IMAP/POP3 servers (Dovecot), using graceful reloads to avoid dropping active connections
• ▹Distribute outbound traffic with HAProxy and network routing (e.g. BGP via FRRouting) and architect high-volume failover
• ▹Administer backend databases (PostgreSQL replicas) and backup/archive servers that take over from a failed primary
• ▹Maintain strict workload isolation between mail, injection (Postal) and archiving nodes
• ▹Maintain flawless DNS and authentication setups (SPF, DKIM, DMARC toward p=reject, BIMI)
• ▹Implement automated MTA-level dynamic throttling to handle 4xx deferrals
• ▹Design and guide automated IP/domain warm-up plans over 2-4 week cycles
• ▹Configure and optimize Rspamd for outbound spam filtering
• ▹Deploy automated connection-dropping systems (Fail2Ban, custom SMTP blocker scripts) against attacks
• ▹Build and maintain a dynamic IP pooling engine (the Penalty Box) to isolate accounts with poor metrics
• ▹Respond to DNSBL listings (e.g. Spamhaus): find the root cause, plug the leak and submit delisting requests
• ▹Build log aggregation pipelines with Vector
• ▹Scan for bandwidth anomalies and compromised credentials with IPAudit and custom tools
• ▹Monitor ISP portals (Google Postmaster Tools, Microsoft SNDS, Yahoo Sender Hub) and third-party tools (GlockApps, Validity/ReturnPath, MXToolbox, DMARCian) daily

Requirements

• ▹5+ years as a Linux systems administrator, DevOps or infrastructure engineer with deep networking knowledge (TCP/IP, routing, ports, DNS)
• ▹Expert-level configuration, debugging and optimization of Postfix, Dovecot or Postal
• ▹Hands-on experience writing rules and maintaining Rspamd and Fail2Ban
• ▹Proven experience building or maintaining log pipelines with Vector or similar
• ▹Experience with network routing tools (HAProxy, FRRouting) and relational databases (PostgreSQL replication)
• ▹Familiarity with automated SSL/TLS certificate rotation and multi-node compliance monitoring
• ▹Deep understanding of the difference between delivery and deliverability
• ▹Expert parsing of aggregate DMARC reports with DMARCian, Valimail or Postmark
• ▹Strict commitment to Acceptable Use Policies and grasp of FBL triage
• ▹Hands-on experience configuring Linux mail servers at the command-line level

Soft skills

What we offer

• ▹Fully remote, global
• ▹Full-time contract role