Koltrix
Comparisons
Campaign Builder or Email API? Where SaaS Lifecycle Mail Should Live
Campaign builders and email APIs solve different halves of lifecycle email. Who should own onboarding, trial and billing mail, and when a hybrid setup works.
4 min read
AI & emailPrivacy questions to ask before turning on AI in email
Privacy questions to ask any vendor before AI reads your team's email: model training, sub-processors, retention, location, admin controls and deletion.
5 min read
DeliverabilityDangling DNS records and email: subdomain takeover risks
Stale CNAMEs and forgotten includes can let someone else send or host content on your domain. How takeovers happen and how to audit DNS for them.
5 min read
GuidesChoosing a Transactional Email API: 12 Questions to Ask
Every transactional email API sends mail. The differences hide in webhooks, suppression, logs, replies and exit. Twelve questions to ask before you commit.
5 min read
Customer supportFeature requests in the inbox: logging them without promising
How to reply honestly to feature requests without committing, log them in the customer's own words, count real demand, and close the loop later.
4 min read
DeliverabilityThe 0.3% spam rate line: how it is measured and avoided
Gmail and Yahoo both draw a line at a 0.3% spam complaint rate and recommend staying under 0.1%. How the rate is calculated and how to keep it low.
4 min read
StartupsUsage Milestone Emails Customers Actually Like
A well-timed milestone email reminds customers what your product did for them. Which milestones are worth celebrating, how to make them useful, and how often.
4 min read
GuidesHow to roll out two-factor authentication for team email
A runbook for enabling 2FA across a team's email accounts: announcing it, choosing apps, storing recovery codes, handling lost phones and verifying everyone.
4 min read
GuidesTracing a delivery through Received headers
Received headers record every hop a message took, newest first. Read them bottom-up to find delays, rewrites and the server that touched your mail.
5 min read
GuidesHow to Choose a Business Email Provider: A Practical Scorecard
Picking a business email provider is mostly a question of which trade-offs you can live with. A weighted scorecard you can copy, with the criteria that matter.
4 min read
Team inboxThe weekly inbox review: a 30-minute ritual for small teams
A minute-by-minute agenda for a 30-minute weekly team inbox review: stale threads, waiting-on-customer, recurring questions, rule tweaks and one change.
4 min read
Email APIVerifying webhook signatures with HMAC: a practical guide
Never trust a webhook until you verify its signature over the raw body. HMAC verification in Node, Python and Go, plus timestamp and replay checks.
5 min read