Email Authentication: Page 4
Browse Palisade articles and guides in Email Authentication.
Proofpoint vs Mimecast: how the two compare
Proofpoint vs Mimecast compared on their own documented terms: deployment, coverage, pricing transparency, and where DMARC sits for each vendor.
Aug 12, 2026
RFC 5321.MailFrom vs RFC 5322.From: what's the difference?
RFC 5321.MailFrom vs RFC 5322.From: learn how SMTP envelope and visible header identities differ, how SPF checks them, and how DMARC alignment works.
Aug 12, 2026
SendGrid one-click unsubscribe: headers, subscription tracking, and validation
Configure or verify SendGrid one-click unsubscribe with Subscription Tracking or custom headers, then inspect a delivered message.
Aug 12, 2026
What does SMTP connection refused mean?
SMTP connection refused means a TCP connection was rejected before SMTP began. Diagnose the endpoint, listener, firewall, DNS, and retry path.
Aug 12, 2026
Spam complaint rate in email: what it means and how to measure it
Your spam complaint rate is spam reports divided by a denominator each provider defines itself, so a Gmail figure and a Yahoo figure are not comparable.
Aug 12, 2026
What is a DMARC failure report?
DMARC failure reports are optional message-level reports about DMARC failures. Learn what they can contain, why delivery varies, and how to use them.
Aug 12, 2026
What is a PTR record and how does reverse DNS use it?
PTR records map an IP address to a hostname. Learn how reverse DNS works, validate forward confirmation, and troubleshoot email sending IPs.
Aug 12, 2026
What is DANE and does your email need it?
DANE uses DNSSEC-signed TLSA records to authenticate SMTP TLS. Learn when email domains need DANE, how it works, and how to validate it safely.
Aug 12, 2026
Why does DMARC fail and how do I fix it?
A DMARC fail means neither SPF nor DKIM passed in alignment with the visible From domain. Identify the source, repair it, and retest the same path.
Aug 12, 2026
Why do Google Group messages go to spam?
Google Group mail fails for reasons ordinary mail does not, forwarding breaks SPF and rewriting breaks DKIM. How to tell which, and what to change.
Aug 12, 2026
Mailchimp SPF record: when do you need one?
Mailchimp DMARC alignment can pass through aligned DKIM without Mailchimp in SPF. Inspect headers, verify DNS, and validate the sending path.
Aug 12, 2026
Why does my DKIM signature fail alignment and how can I fix it?
DKIM signature alignment fails when a passing DKIM d= domain does not align with the visible From domain. Inspect headers, fix signing identity, and.
Aug 12, 2026
Why is phishing so effective?
Phishing works by pairing trusted-looking context with pressure and a simple requested action. Learn how to interrupt the decision safely.
Aug 12, 2026
Yahoo bulk sender requirements
Yahoo bulk sender requirements: authentication, DMARC alignment, unsubscribe, complaint-rate, DNS, and validation checks for Yahoo Mail senders.
Aug 12, 2026
How do you authenticate an email for Gmail?
Authenticate email for Gmail with SPF, DKIM, and DMARC, then validate the exact sending path in Gmail headers and DMARC reports, and verify sender paths.
Aug 12, 2026
Google's stricter email sender rules (Nov 2025)
Google's stricter email sender rules: track Gmail's authentication, alignment, TLS, DNS, spam-rate, and unsubscribe requirements after Nov 2025.
Aug 12, 2026
Why does Gmail report an SPF error?
Gmail SPF errors mean Gmail could not authorize the sending IP for the envelope domain it evaluated. Inspect headers, repair the SPF path, and retest now.
Aug 12, 2026
Why does DMARC say an rua or ruf domain is not authorized?
DMARC says an rua or ruf domain is not authorized when an external report destination lacks the DNS consent record required for that policy domain.
Aug 11, 2026
How long does DNS propagation take for email records?
DNS changes take effect as cached copies expire, not on a fixed timer. What TTL controls for MX, SPF, DKIM and DMARC, and how to verify a change landed.
Aug 11, 2026
Can an email have multiple DKIM signatures?
Can an email have multiple DKIM signatures? Yes. Learn how receivers verify each signature and which passing signature can satisfy DMARC in practice.
Aug 11, 2026
How do you manage multiple DKIM records for one domain?
How to manage multiple DKIM records: use unique selectors, publish each key safely, rotate without breaking mail, and validate delivered messages.
Aug 11, 2026
How often should you rotate DKIM keys?
How often should you rotate DKIM keys? DKIM sets no universal interval. Use a documented risk-based schedule and rotate immediately after exposure.
Aug 11, 2026
What is the DMARC np tag and how do you use it?
The np tag applies a policy to subdomains that do not exist, closing the gap attackers use to spoof made-up subdomains. When to add np=reject, and when not to.
Aug 11, 2026
DNS TXT SPF record: what it is and how it works
An SPF policy is published in DNS as a TXT record starting with v=spf1. Learn the record format, size limits, and how to check if your domain has one.
Aug 11, 2026