Koltrix
Startups
Onboarding Calls or Onboarding Emails? Choosing by Account Size
When a live onboarding call earns its cost, when self-serve email onboarding is enough, and how to write the emails that book, recap and rescue those calls.
5 min read
Team inboxHow founders hand off the inbox to their first hire
A staged playbook for founders handing customer email to their first hire: shadowing, reviewed replies, owning a category, then owning the whole inbox.
5 min read
Email APIIdempotency keys for email: preventing duplicate sends
A client retry after a timeout should never email a customer twice. How idempotency keys work, the race people miss and how to pick key values.
4 min read
StartupsTurning a Changelog Into Product Update Emails People Read
A changelog is written for the team that shipped. A product update email is written for the customer. How to pick what goes out, group it, and keep it short.
4 min read
Customer supportClosing the loop: following up after a fix ships
A runbook for telling customers their bug is fixed: track who reported it, write the follow-up, confirm it works, and handle the cases where it does not.
5 min read
DeliverabilityDKIM header oversigning and why the l= tag is a trap
Which headers to sign, why signing From twice blocks header injection, and how the l= body length tag lets attackers append content to signed mail.
5 min read
ComparisonsFront vs Help Scout vs a Plain Shared Inbox
Front, Help Scout and a plain shared mailbox solve overlapping problems for different teams. A fair look at who each one suits, at the time of writing.
5 min read
AI & emailCatching hallucinated facts in AI email replies
AI drafts can invent features, dates, policies, links and names. Five worked examples of each kind of error, plus a habit that catches them before sending.
5 min read
DeliverabilityReverse DNS for mail servers: PTR, FCrDNS and HELO
Receivers expect a sending IP to have a PTR record that resolves back to the same IP and a sane HELO name. Configure all three and verify them.
4 min read
GuidesHelp Desk or Shared Inbox? Deciding at Each Company Stage
A shared inbox is enough for longer than most teams think, and a help desk is right sooner than some admit. How to decide at each stage of a company.
4 min read
Team inboxDiscussing a customer email with teammates, without forwarding
Forwarding customer emails around the team forks threads and leaks context. Here are better ways to discuss a message internally and agree who replies.
5 min read
Email APIProtecting email API keys: scopes, rotation, leak response
An email API key is the power to send as your domain. Scope keys narrowly, store them safely, rotate them on a schedule and respond fast to leaks.
4 min read