Koltrix
Team inbox
Shared inbox for a two-person startup: the minimum setup
The smallest shared inbox setup that works for two founders: one domain, a few addresses, a handful of labels, one reply rule and a weekly 15-minute review.
4 min read
DeliverabilityLocking down domains that never send email
Unused domains are easy spoofing targets. Publish a null MX, a deny-all SPF record and a reject DMARC policy so nobody can send mail as them.
4 min read
StartupsEmail for Health-Tech Startups: Practical Privacy Habits
Health-tech teams email patients, clinicians and partners. Practical habits that keep sensitive details out of inboxes, with a clear note on what needs counsel.
5 min read
GuidesHow to write a prompt that summarizes a long email thread
Build a reliable prompt for summarizing long email threads: purpose, audience, a fixed output format, exact numbers and flagged uncertainty, plus an example.
5 min read
Email APIModeling email events in your database
Store email delivery events in an append-only table, derive message status from it, and keep the history you need to answer support questions.
5 min read
ProductWhat Koltrix Doesn't Do Yet, and Who Should Wait
An honest list of what Koltrix v1 doesn't include, from IMAP and importers to SOC 2 and SDKs, and the teams for whom waiting or choosing another tool is right.
5 min read
Customer supportWriting support emails people actually read
How to write support replies customers read to the end: answer first, short paragraphs, numbered steps, one question at a time, and a before-and-after rewrite.
5 min read
DeliverabilityLookalike domains: detecting cousin-domain phishing
Typo and homoglyph domains pass authentication for themselves. Monitor new registrations, register obvious variants and train people to check senders.
4 min read
ComparisonsDedicated Lifecycle Email Tool or In-House Code? How to Decide
Buying a lifecycle messaging platform or writing onboarding and trial emails in your own code: who owns copy, testing and cost on each side, with a checklist.
5 min read
AI & emailRead, organize, draft, never send: a capability model for AI email
A five-tier capability model for AI in email: read, organize, draft, send and delete, with the risk and reversibility of each and why the line sits before send.
5 min read
Email APIEmail validation at signup: what to check, and what not to
Validate signup addresses with syntax checks, domain and MX lookups and typo suggestions, but skip SMTP probing. A layered approach with code.
4 min read
StartupsEmail Operations for Fintech Startups: Clarity and Audit Trails
Money-related email needs precise copy, consistent senders and records you can find later. Operational habits for fintech startups, from notices to phishing.
5 min read