Koltrix
Deliverability
Aligning DKIM when a vendor sends on your behalf
CRM, billing and support tools often sign with their own domain. How to get vendor mail DKIM-aligned with your From domain before enforcing DMARC.
4 min read
Blog · Deliverability · page 2 of 5
Deliverability
SPF, DKIM, DMARC, BIMI, sender reputation and the inbox rules of Gmail, Yahoo and Microsoft: what decides whether your email arrives.
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
DeliverabilityGoogle Postmaster Tools: the dashboards that matter
Postmaster Tools is the only first-party view into how Gmail sees your domain. Set it up, read the spam rate and compliance views, and know its blind spots.
4 min read
DeliverabilitySeparate subdomains for transactional and marketing mail
Splitting streams across subdomains contains reputation damage. How to structure them, align SPF and DKIM per subdomain, and what it cannot protect.
4 min read
DeliverabilityMicrosoft SNDS and JMRP: monitoring Outlook reputation
SNDS shows how Outlook.com rates your sending IPs; JMRP forwards complaints. How to enroll, what the colors mean and how to act on the data.
5 min read
DeliverabilityRotating DKIM keys without dropping a single message
A selector-based DKIM rotation plan: publish the new key, switch signing, keep the old key long enough, then revoke it with an empty p= tag.
4 min read
DeliverabilityCustom tracking domains and why shared link domains hurt
Click tracking rewrites links through a redirect domain. If that domain is shared, its reputation becomes yours. Set up a branded one with HTTPS.
4 min read
DeliverabilityDomain reputation vs IP reputation: which is hurting you?
Modern filters weigh your domain more heavily than your IP, but both matter. How to tell which one is dragging placement down and what fixes each.
4 min read
- Deliverability
Five deliverability metrics worth alerting on
Skip vanity numbers. Alert on deferral rate, hard bounce rate, complaint rate, authentication failures and delivery latency, with sensible thresholds.
5 min read
DeliverabilityHow to read a DMARC aggregate report, line by line
DMARC aggregate reports are compressed XML that few people read. Walk through each element, what the counts mean, and how to spot spoofing quickly.
5 min read
DeliverabilityDKIM body hash did not verify: the usual suspects
When DKIM fails with a body hash mismatch, something changed the message after signing. Find the culprit: footers, rewriters, line endings, encoding.
4 min read
- Deliverability
Inbox placement testing: seed lists, panels and limits
Seed tests show where a message lands for test accounts, not for your users. What seed lists and panel data can tell you and how to use them honestly.
4 min read