Koltrix
Guides
From a Personal Gmail to a Custom-Domain Address
When to move your business off a personal Gmail address, how to tell contacts, which accounts to update first, and the registrar mistake that locks people out.
4 min read
Team inboxNaming team addresses: support@, hello@, billing@ and beyond
Which role-based email addresses a SaaS team needs at each stage, naming conventions that age well, where to publish each one, and the catch-all trap to avoid.
4 min read
DeliverabilityHow email spoofing works and which records stop it
SMTP lets anyone claim any From address. Follow a spoofed message through a receiver and see exactly where SPF, DKIM and DMARC stop it, and where not.
5 min read
Customer supportChurn Signals Hiding in Your Support Inbox
Customers often signal they're about to leave long before they cancel, just not in so many words. What to look for in support email, plus a weekly routine.
5 min read
GuidesHow to set up a support@ shared mailbox on your own domain
A step-by-step runbook for a support@ shared mailbox on your own domain: verify the domain, authenticate, grant access, add labels, auto-reply and test it.
5 min read
Email APIAttachments in transactional email: size, type, options
Attaching invoices and reports raises size, security and deliverability concerns. When to attach, when to link, and how to keep attachments safe.
4 min read
StartupsDunning Emails That Recover Failed Payments Without Anger
A five-email dunning sequence for failed SaaS payments: what each message says, when it goes out, and copy rules that recover revenue without upsetting anyone.
4 min read
Customer supportWriting the first support reply: acknowledge, clarify, commit
A three-part structure for the first reply to a support email, with worked examples for a bug report, a billing question and a how-to, plus questions to ask.
5 min read
- Deliverability
Transactional vs marketing mail under bulk sender rules
Which bulk sender rules apply to receipts and password resets, which apply only to marketing, and why mixing both streams on one domain is risky.
4 min read
ComparisonsZoho Mail vs Google Workspace for Small Businesses
Zoho Mail or Google Workspace for a small business? Suite breadth, budget, collaboration, spam filtering and hosting regions compared, with who each one suits.
4 min read
AI & emailPrompt injection in email: what it is and why inboxes are exposed
Email is untrusted text written by anyone. Here is how prompt injection works against AI email assistants, how attackers hide instructions, and what they want.
5 min read
GuidesA 30-minute email authentication audit for your domain
A timed checklist to audit SPF, DKIM, DMARC and transport security on any domain, with the commands to run and what a passing answer looks like.
4 min read