Email and DNS Administration

Sysadmin help for DNS, SPF, DKIM, DMARC, mail delivery, Exim, Postfix, Dovecot, blacklists, mail queues and email infrastructure troubleshooting.

Email and DNS That Actually Work

Email delivery problems and DNS misconfigurations are among the most common reasons businesses contact us. A single missing record can cause messages to land in spam, bounce entirely, or expose your domain to spoofing. HireSysAdmin provides hands-on sysadmin work to get your email and DNS infrastructure into a reliable, standards-compliant state.

DNS Administration

  • Zone file management and record auditing
  • MX record configuration and priority planning
  • SPF records — correct syntax, include mechanisms, lookup limits
  • DKIM key generation, DNS publishing, and selector rotation
  • DMARC policy setup, reporting configuration, and gradual enforcement
  • Reverse DNS (PTR) records for outbound mail servers
  • TTL planning for migrations and failover
  • CNAME, A, AAAA, TXT, SRV, and CAA record management
  • Split-horizon DNS and internal/external zone coordination

Mail Server Administration

  • Exim configuration, routing rules, ACLs, and queue management
  • Postfix transport maps, relay configuration, and TLS enforcement
  • Dovecot IMAP/POP3 setup, authentication backends, and mailbox formats
  • SMTP authentication hardening and relay restriction
  • Mail queue inspection, clearing stuck messages, and retry scheduling
  • Mail routing for split delivery (some mailboxes on-server, some external)
  • Mailbox migration between servers, platforms, or providers
  • Bounce analysis and NDR troubleshooting
  • Rate limiting and outbound throttling for shared environments

Common Problems We Handle

  • Emails going to spam — missing or broken SPF, DKIM, or DMARC records; poor sender reputation; content triggers
  • Blacklisted server IP — delisting requests, identifying the source of abuse, preventing recurrence
  • Mail queue growing — remote server rejecting, DNS resolution failures, authentication errors, resource exhaustion
  • Delivery delays — greylisting, DNS timeouts, connection throttling, oversized queues
  • Wrong MX records — mail routing to the wrong server after a migration or provider change
  • Missing PTR record — outbound mail rejected by recipients that enforce reverse DNS checks
  • DKIM verification failures — selector mismatch, key rotation issues, DNS propagation
  • DMARC spoofing alerts — unauthorized senders using your domain, policy not enforced
  • Mailbox migration issues — missing folders, broken permissions, authentication failures after move

How We Work

Every engagement starts with a clear scope. We assess the current state of your DNS and email configuration, identify what needs to change, execute the work, and verify the result. No ongoing commitment is required for one-time fixes, though many clients pair this with a monitoring retainer for continued oversight.

Get Started

If your email is unreliable or your DNS needs attention, contact us to describe the issue. We will respond with a clear scope and pricing before any work begins. For ongoing needs, see our retainer plans.

Need help with this?

Tell us what you need and we will scope the work.

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