Koltrix
Deliverability
Gmail and Yahoo bulk sender rules: the full checklist
What Gmail and Yahoo require from senders of roughly 5,000 messages a day: SPF and DKIM, DMARC, alignment, one-click unsubscribe and spam rates.
4 min read
DeliverabilityOutlook.com's requirements for high-volume senders
Microsoft now expects SPF, DKIM and DMARC from domains sending over 5,000 messages a day to Outlook.com, Hotmail and Live. What to check and fix.
4 min read
Email APIImplementing one-click unsubscribe (RFC 8058) correctly
One-click unsubscribe needs two headers, a DKIM signature that covers them, and an endpoint that accepts a POST without a login. Build it step by step.
5 min read
DeliverabilityTransactional vs marketing mail under bulk sender rules
Which bulk sender rules apply to receipts and password resets, which apply only to marketing, and why mixing both streams on one domain is risky.
4 min read