Koltrix
Startups
The Monthly Investor Update Email: A Founder's Template
A plain, repeatable template for monthly investor updates: highlights, lowlights, metrics, asks and thanks, plus how to send it and what to do with the replies.
4 min read
Customer supportTurning support email into a knowledge base
A worked example: mine a quarter of support threads for repeat questions, write help articles in customer words, link them in replies, keep them fresh.
5 min read
DeliverabilityWarming up a brand-new sending domain
A new domain has no reputation, which filters treat with suspicion. Authenticate first, start with your most engaged recipients and grow steadily.
5 min read
GuidesWhat Business Email Really Costs a Five-Person Startup
Mailboxes are only one line on the bill. A framework for adding up what email really costs a five-person startup, including sending, support tools and time.
4 min read
Team inboxWhy forwarding team mail to personal inboxes breaks at scale
Forwarding hello@ and support@ to personal inboxes works for a while. A teardown of how it fails: lost history, wrong reply addresses, offboarding gaps.
4 min read
Email APIFeedback loops and ARF: turning complaints into suppressions
Mailbox providers report spam complaints as ARF messages. Parse them, map them back to the recipient and suppress automatically within minutes.
4 min read
StartupsFreemium Upgrade Emails: Moving Free Users to Paid Without Nagging
Freemium has no deadline, so upgrade emails must be triggered by value and limits, not dates. Which triggers work, what to write, and when to leave users alone.
5 min read
AI & emailAuditing what an AI assistant did in your mailbox
Why every AI tool call in your mailbox should be logged, what a good audit trail records without storing mail content, a weekly review routine and red flags.
4 min read
GuidesPublishing a 2048-bit DKIM key when DNS splits strings
A 2048-bit DKIM public key exceeds the 255-character TXT string limit. How string splitting works, provider quirks, and how to verify the result.
4 min read
StartupsA Founder's Weekly Email Operations Routine
A one-hour weekly routine that keeps a startup's email healthy: bounces, lifecycle messages, support threads, open promises and DNS. Plus how to hand it off.
4 min read
AI & emailAI for non-English email: translation and drafting caveats
Using AI to read and answer email in other languages: formality, idioms, names, verifying critical lines, telling customers, and keeping a shared glossary.
5 min read
DeliverabilityEd25519 DKIM: should you dual-sign yet?
RFC 8463 added Ed25519 to DKIM, but receiver support is uneven. Learn how dual signing with RSA works and whether it is worth the operational cost.
4 min read