Email AuthenticationDMARC generates aggregate reports showing exactly who is sending as your domain and whether authentication is passing. Most senders never read them — but they contain everything you need to advance from monitoring to enforcement safely.
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Email AuthenticationSPF records authorize which IP addresses can send email from your domain — but they break in specific ways that are easy to miss. The 10-lookup limit, duplicate record conflicts, and forgotten sending services are the most common culprits behind SPF failures.
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Email AuthenticationDKIM key rotation limits your exposure if a signing key is ever compromised — but doing it wrong breaks email authentication in transit. This guide covers the safe rotation sequence, including why you must keep the old public key in DNS for 48–72 hours after switching.
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DeliverabilityEmail headers document every hop a message takes — authentication results, timestamps, and server paths. Knowing how to read them turns a mysterious delivery failure into a traceable, fixable problem.
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DeliverabilityGetting off an email blocklist requires fixing the root cause before requesting removal. This guide covers how to identify which lists you are on, what typically causes listings, and how to work through the delisting process for Spamhaus, Barracuda, and SpamCop.
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Email SecuritySTARTTLS encrypts email in transit opportunistically — but that leaves it vulnerable to downgrade attacks. DANE and MTA-STS enforce TLS and close that gap. This guide explains how each mechanism works and what they protect against.
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SMTP & InfrastructureEmail APIs let developers send transactional email with an HTTP request — but deliverability, error handling, domain authentication, and webhook processing all need to be wired up correctly for it to work reliably at scale.
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DNS & DomainsDNS TTL values control how long records are cached — and setting them wrong means waiting unexpectedly long for changes to take effect. This guide covers the right TTL values for MX, SPF, DKIM, and DMARC records, and how to prepare for DNS changes without surprises.
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SMTP & InfrastructureA mail server connected to the internet is a high-value target for open relay abuse, spam injection, and phishing attacks. This checklist covers SMTP hardening essentials — from closing open relays and enforcing TLS to rate limiting, authentication records, and monitoring.
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