Understanding Feedback Loops (FBLs) With ISPs
Feedback loops let major mailbox providers notify senders directly when a recipient marks their mail as spam, giving senders visibility they otherwise wouldn't have into real-time complaint behavior.
Understanding PTR Records and Reverse DNS
A PTR record maps a sending IP address back to a hostname, and its presence and consistency are checked by nearly every major receiving provider as a basic legitimacy signal.
Understanding the Google and Yahoo Bulk Sender Requirements
Any domain sending 5,000 or more messages per day to Gmail or Yahoo addresses is classified as a bulk sender and held to a specific, enforced set of technical requirements.
Understanding TLS in Email Transmission
Transport Layer Security encrypts the connection between mail servers during transmission, and its presence or absence is increasingly factored into deliverability decisions.
Using a Subdomain Strategy to Protect Your Root Domain
Sending marketing or transactional mail from a dedicated subdomain, rather than the root domain, isolates reputation risk and keeps unrelated business functions protected.
What Is IP Warming and Why It Still Matters
A new sending IP has no established reputation, and warming it up gradually is still a necessary technical practice for building the trust receiving providers require.
Building a Basic Deliverability Monitoring Checklist
A simple, consistent checklist applied on a regular cadence catches deliverability problems while they're still small and easy to fix.
Common DKIM Signing Mistakes That Break Alignment
DKIM can technically pass while still failing DMARC alignment, a subtle but common failure mode that trips up many senders relying on third-party email service providers.
DKIM Signing Explained: Keys, Selectors, and Headers
DKIM (DomainKeys Identified Mail) adds a cryptographic signature to outgoing messages, letting receiving servers verify the message wasn't altered in transit and genuinely originated from the claimed…
DMARC Explained: Policy, Alignment, and Reporting
DMARC (Domain-based Message Authentication, Reporting, and Conformance) ties SPF and DKIM together, adding a policy for how receiving servers should handle authentication failures and a reporting…
How Inbox Placement Differs From Delivery
Understanding the specific technical checkpoint where a message can succeed at "delivery" but fail at "inbox placement" clarifies where deliverability problems actually originate.
Moving From p=none to p=quarantine to p=reject Safely
Progressing a DMARC policy toward full enforcement is a deliberate, staged process, and jumping straight to reject without proper visibility first risks silently blocking legitimate mail.
Reading and Interpreting DMARC Aggregate (RUA) Reports
Aggregate reports are the primary technical tool for understanding exactly which sources are sending mail as your domain and whether they're passing authentication.
Reading DMARC Forensic (RUF) Reports
Forensic reports provide detailed, per-message failure data, offering more granular diagnostic detail than aggregate reports, though with important privacy and adoption caveats.
Shared IP vs. Dedicated IP: Technical Tradeoffs
Choosing between a shared and dedicated sending IP is a genuine technical tradeoff, not a simple upgrade decision, and the right choice depends on sending volume and consistency.
SPF Records Explained: Syntax and How They Work
SPF (Sender Policy Framework) publishes a list of servers authorized to send mail on behalf of a domain, letting receiving servers verify a message's origin.
The SPF 10-DNS-Lookup Limit and How to Avoid Exceeding It
SPF enforces a hard limit of 10 DNS lookups during evaluation, and exceeding it causes the entire SPF check to fail, a common and often overlooked technical trap.
Understanding Bounce Types: Hard Bounces vs. Soft Bounces
Correctly distinguishing bounce types, and handling each appropriately, is a foundational technical practice that directly protects sender reputation.
Understanding DMARC Alignment: SPF vs. DKIM Alignment Modes
DMARC alignment can be configured as strict or relaxed for both SPF and DKIM independently, and understanding the difference affects how forgiving your policy is toward legitimate but imperfectly…
Understanding Sender Score and Domain Reputation
Reputation is tracked separately by different receiving providers, and understanding how it's built and eroded is essential for diagnosing deliverability problems.