Communications, email, nurture, Resend

Communications are the seam between your product and the rest of the world. Leads come in. Confirmations go out. Customers get nurtured. Without this seam, everything you build is invisible to anyone outside your machine.

Most participants overestimate how hard this is. The honest truth: send-an-email-from-code is now a fifteen-minute task. Send-a-text-message is similar.

Two channels carry 95% of business comms

You can spend years on the long tail of channels (WhatsApp Business, Telegram, push, in-app, RCS). Or you can start with the two that cover almost every real use case.

• Email, the primary channel
  Resend is the IL default. Sign up, verify your domain, send by calling one API. Built by ex-GitHub, modern API, generous free tier.
• SMS, the secondary channel
  Twilio is still the default for reliable delivery. Same shape: sign up, verify a number, send via API. Use sparingly; SMS costs money per send and goodwill per send.

Two kinds of email, different tools

Mixing these up is the most common deliverability mistake.

• Transactional
  Triggered by an action: signup confirmation, password reset, order receipt, lead-form notification. One-to-one tone. Resend is purpose-built for this.
• Newsletter / bulk
  Many recipients, scheduled, one-to-many tone. Use MailChimp, ConvertKit, or Resend's bulk plan. Keep the sending domain separate from transactional so a bad campaign cannot tank your password-reset deliverability.

Deliverability: three letters that decide inbox vs spam

Email arrives in the inbox or the spam folder based on three DNS records. Resend walks you through all three; you copy/paste them into your DNS settings once and never think about them again.

• SPF
  Says: these IP addresses are allowed to send mail as my domain.
• DKIM
  Signs every email with a cryptographic key. Receiving servers verify the signature.
• DMARC
  Tells receiving servers what to do if SPF or DKIM fails. Start with p=none (monitor), tighten over time.

The non-optional pieces

Every nurture email needs an unsubscribe link in the footer. An unsubscribe is honored instantly and forever. Every SMS needs reply STOP. Consent is recorded with a date. CAN-SPAM (US), GDPR (EU) and the Australian Spam Act all require these. Resend and Twilio handle the mechanics; you have to remember to include them.

The nurture shape

A lead that lands and hears nothing for a week is the most common failure in a small business. The fix is a small machine, and every nurture campaign you will ever build has the same five parts.

• Enrol on a trigger
  The contact form handler adds a row to nurture_enrollments: who, which sequence, step 1, next send now. Anyone already enrolled or unsubscribed never enrols twice.
• Store the step and the next send time
  One row per person per sequence. The row knows where they are and when they are due. The whole state of the campaign is a table you can read.
• A scheduled job sends what is due
  A Vercel cron route wakes every 15 minutes, protected by a secret. It sends every enrollment whose next_send_at has passed, records the send with the Resend id, and advances the step. Idempotent: it never sends the same step twice.
• Unsubscribe flips one row
  Every email carries a signed unsubscribe link. Click it, the row is marked, a plain confirmation page shows, and nothing more sends. Ever.
• Test mode first
  A TEST_MODE flag compresses the delays to minutes and rewrites every recipient to your own inbox, so you watch the whole sequence land before a real person ever gets one. Never send to a synthetic person.

Your contact form sends a real email to the lead and a notification to you. Resend is wired with verified DNS. You have crossed from has-a-form to has-a-funnel, and the nurture machine is the next block.