spf-all-qualifier

Email authentication: SPF, DKIM, DMARC, BIMI and MTA-STS

SPF +all and ?all: Why They're Dangerous in 2026

Stop risking your sender reputation. Learn why SPF +all and ?all are dangerous, how they break email authentication, and how MailTester’s verification API.

Email authentication: SPF, DKIM, DMARC, BIMI and MTA-STS

Does SPF -all Improve Inbox Placement or Just Security?

Discover whether SPF -all boosts inbox placement or just strengthens security. Learn the real impact on deliverability and avoid common pitfalls with real.

Email authentication: SPF, DKIM, DMARC, BIMI and MTA-STS

SPF ~all vs -all: Which Is Better for Deliverability?

Discover whether SPF ~all or -all is better for deliverability. Learn how softfail vs hardfail impacts inbox placement and sender reputation in 2026.