Koltrix
Guides
DNS TTL strategy for email authentication changes
Lower TTLs before you change SPF, DKIM or MX, and know which caches ignore you. A practical timeline for authentication changes without surprises.
5 min read
Blog · Guides · page 4 of 6
Guides
Step-by-step how-tos and migration checklists you can follow from start to finish.
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
GuidesHow to write a one-page support playbook
A fill-in-the-blanks template for a single-page support playbook: addresses, owners, hours, triage, escalation, refunds, tone, and the links people need.
5 min read
Guidesdig commands every email engineer should know
The dig queries that answer most email questions: SPF, DKIM selectors, DMARC, MX, PTR, MTA-STS and BIMI, plus how to bypass caches when testing.
5 min read
GuidesThe Minimal Email Stack for a Pre-Seed SaaS
Before product-market fit, your email setup should be small, cheap and reliable. The four pieces a pre-seed SaaS needs, and what to put off until later.
4 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
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
GuidesSwitching Transactional Email Providers With Zero Downtime
Moving your app's email to a new provider doesn't need a risky big-bang cut-over. Dual DKIM, a thin sending interface, gradual rollout and suppression export.
4 min read
GuidesSMTP enhanced status codes (RFC 3463), decoded
Enhanced status codes like 5.1.1 and 4.7.0 say why delivery failed. Learn the class.subject.detail structure and the codes you will see most often.
5 min read
GuidesHow to audit a messy shared inbox in one afternoon
An hour-by-hour runbook for cleaning up a neglected shared inbox: take stock, clear the noise, rescue waiting threads, fix labels, and add three useful rules.
4 min read