Peter Mastras
Director & Lead Engineer
I founded Edos Solutions in 2005 to handle the infrastructure work most IT providers avoid — production mail systems, security hardening, complex server environments. The stuff that's unglamorous but critical to how businesses actually run.
Over 20 years I've managed email infrastructure and server environments for Australian businesses across financial services, legal, healthcare, government and resources — diagnosing deliverability failures, hardening servers, migrating Exchange tenants, and building the automation that keeps production systems running without constant human intervention.
I write the articles on this site from production experience, not theory. When I describe an SPF lookup limit failure or a DMARC misalignment, it's because I've diagnosed it in a live environment and fixed it.
20+ years of production infrastructure experience.
- Email infrastructure — Exchange, Postfix, Dovecot, Office 365
- Email authentication — SPF, DKIM, DMARC, MTA-STS, BIMI
- Mail security gateways — inbound/outbound filtering, quarantine management
- Linux server management — Debian, Ubuntu, RHEL/AlmaLinux
- Windows Server — Active Directory, Group Policy, IIS
- Cybersecurity — hardening, pen-test remediation, security header implementation
- AI integration — document processing pipelines, internal tools, workflow automation
- Deliverability — blacklist monitoring, RBL delisting, DMARC aggregate reporting
Written from production experience.
- email 18 June 2026 6 min read
How to set up MTA-STS and TLS-RPT for your domain
MTA-STS forces sending servers to use TLS when delivering to your domain, preventing downgrade attacks. Here's how to configure the policy file, DNS records, and TLS-RPT reporting.
Read article - email 11 June 2026 7 min read
Why Microsoft 365 DMARC failures happen and how to fix them
DMARC failures in Microsoft 365 environments usually trace back to one of four causes. Here's how to identify which one is happening on your domain and fix it.
Read article - security 4 June 2026 8 min read
Linux server hardening: a practical checklist for production
A working checklist for hardening a Linux server in production: SSH, firewall, fail2ban, automatic updates, audit logging and more. Built from real environments.
Read article - email 28 May 2026 7 min read
How to check if your mail server is blacklisted and get it delisted
A blacklisted sending IP is rejected at the SMTP level before your message is assessed. How to check the major blacklists, read the results, and get the listing removed.
Read article - email 28 May 2026 7 min read
MTA-STS: stop attackers from reading your inbound email in transit
Without MTA-STS, attackers on the network path to your mail server can strip TLS and read your inbound email in plaintext. Here's what MTA-STS does, how to deploy it, and how to verify it's working.
Read article - email 21 May 2026 8 min read
Migrating Exchange to Microsoft 365: four email delivery problems nobody warns you about
Most Exchange to M365 migration guides focus on mailbox data. The email delivery problems that appear after cutover — broken DKIM, orphaned SPF includes, hybrid flow issues — get less attention. Here's what to fix before and after you flip the MX record.
Read article - email 14 May 2026 6 min read
Setting up DKIM in Microsoft 365: what the documentation misses
DKIM is disabled by default in Microsoft 365. The setup involves CNAME records and a non-obvious activation step in the admin centre — and there are several ways it silently fails.
Read article - email 7 May 2026 7 min read
Reading DMARC aggregate reports: what the XML actually tells you
DMARC aggregate reports arrive as compressed XML. Most people never look at them. Here's what every field means, what failure patterns to watch for, and how to act on the data.
Read article - email 29 October 2025 4 min read
Why Microsoft 365 DKIM stops signing your email — and how to fix it
Exchange Online DKIM signing can silently stop working after licence changes, domain modifications or tenant reconfigurations. Here's how to detect it and re-enable it.
Read article - email 8 October 2025 5 min read
DMARC's p=none policy does nothing useful — here's what to do instead
A DMARC record with p=none doesn't protect your domain or affect delivery. It just collects reports. Here's how to read those reports and move to enforcement.
Read article - email 24 September 2025 4 min read
The SPF 10-lookup limit: why it breaks email delivery
RFC 7208 limits SPF evaluation to 10 DNS lookups. Exceeding it invalidates your SPF record and causes intermittent delivery failures. Here's how to count your lookups and fix it.
Read article - email 10 September 2025 5 min read
Why your email is going to spam — and how to fix it
SPF, DKIM and DMARC failures account for most email deliverability problems. Here's how to diagnose and fix each one.
Read article
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