A booking is only as good as its confirmation. If the email with the date, the address and the change link never arrives, the customer wonders whether the booking worked, phones you, double-books or simply does not show up. Likewise, if a lead alert lands in your spam folder, a hot enquiry waits for days. Yet email delivery is one of the least visible parts of any booking or chat system, and one of the most common causes of quiet failure. This guide explains how transactional emails, the automatic messages triggered by an action, are sent and why they sometimes fail to arrive. It covers the difference between sending through an email service and through an SMTP relay, the from address, the DNS records that prove you are legitimate, how to write emails that mail providers trust, how to test properly and what to check when messages go missing. In Crescelo, booking confirmations, reminders and lead alerts are sent by email, and the sending service, SMTP or Resend, is configured by the platform operator; the principles below apply to whoever runs it and help you diagnose delivery problems.
What are transactional emails
| Tipo | Trigger | Example |
|---|---|---|
| Booking confirmation | A visitor books an appointment | Date, time, place, private link to change or cancel |
| Reminder | A set time before the appointment | Reminder with the same link |
| Lead alert | A visitor leaves contact details | Notification to your team with the conversation |
| Password and sign-in | Account actions | Reset link, verification |
They differ from marketing emails: they are expected, individual and time-sensitive. Mail providers generally treat them more favourably, as long as the sender is properly identified.
Two ways to send: an email service or an SMTP relay
| Option | What it is | Good for |
|---|---|---|
| Email API service (such as Resend) | A provider you send through by API, with a dashboard, domain verification and delivery tracking | Simple setup and good deliverability tooling |
| SMTP relay | A standard mail server you connect to with a host, port, username and password | Using an existing mail provider or company server |
Both work. What matters more is that the sending domain is verified and authenticated. Crescelo supports either: the platform operator sets a Resend key or SMTP host, port, user and password, and the from address.
The from address matters
- Use an address on a domain you own, such as bookings@yourbusiness.com, not a free webmail address. Providers reject or spam-folder mail that claims to be from Gmail or Outlook but is sent by another server.
- Use a consistent, recognisable name: 'Riverside Dental' rather than 'noreply'.
- Set a reply-to address that a person reads, so customers can respond.
- Avoid changing the from address often; providers learn to trust a stable sender.
- Do not use a placeholder test address, such as an onboarding address supplied by the service, for real customers; it is meant for trials and has restrictions.
Authenticate your domain: SPF, DKIM and DMARC
These three DNS records tell mail providers that the messages are legitimate. Without them, even perfect emails are often treated as suspicious, especially by Gmail and Yahoo, which now expect authentication from senders. In short:
- SPF lists the servers allowed to send for your domain.
- DKIM signs each message so it cannot be forged or altered.
- DMARC tells receivers what to do with mail that fails, and sends you reports.
Your email service shows the exact records to add and a button to verify them. Follow the step-by-step guide: how to set up SPF, DKIM and DMARC.
Write emails that providers and people trust
| Do | Avoid |
|---|---|
| A clear subject: 'Your appointment on Tuesday 14 May at 10:30' | Vague or shouting subjects, or 'RE:' tricks |
| Plain text alongside simple HTML | Images-only emails |
| Your business name and address in the footer | Anonymous senders |
| One or two links, to your own domain | Many links or shortened URLs |
| Concise, useful content | Long marketing copy in a confirmation |
| A visible way to reply or contact you | No-reply dead ends |
A confirmation should answer: what, when, where, what to bring, how to change it and how to reach you. Crescelo's confirmation includes a private link to change or cancel and an add-to-calendar option, and reminders repeat the essentials.
Test properly
- Send a real booking through your live flow, not just a test button.
- Try several recipients: Gmail, Outlook, Yahoo and a business address.
- Check inbox, spam and promotions folders.
- Open the message headers and check that SPF, DKIM and DMARC show pass.
- Use an email-testing tool or your service's dashboard to see delivery status.
- Test on a phone: is the layout readable and are the links tappable?
- Repeat after any change to the sending service, the domain or the templates.
When emails go missing: a checklist
| Symptom | Likely cause | What to do |
|---|---|---|
| Nothing arrives anywhere | Sending service not configured or credentials wrong | Check the configuration and the service's logs |
| Arrives in spam | Domain not authenticated, or a new domain with no reputation | Set SPF, DKIM and DMARC; send low volumes at first |
| Works for some providers only | Provider-specific filtering | Check headers for pass or fail; look at the provider's postmaster tools |
| Delayed | Queueing or throttling | Check rate limits at the service |
| Bounces | Invalid recipient address | Check for typos; validate addresses at capture |
| Alerts go to the wrong person | Notification address wrong | Update the alert recipient in your settings |
| Reminders never sent | Reminder feature or schedule not running | Check settings and that the scheduled job is active |
Protect your reputation
- Send only to people who asked for the message.
- Keep bounce rates low by validating addresses at capture.
- Honour requests to stop receiving reminders where you offer them.
- Do not use confirmations for promotions.
- Monitor complaints and delivery reports.
- Warm up a new sending domain gradually.
Reputation is built over time. A domain that sends a few genuine confirmations each day and never annoys people is trusted quickly.
Ask customers to help
Mention on your booking page and in the assistant's answers: 'Your confirmation comes from bookings@yourbusiness.com. If you do not see it within a few minutes, please check your spam folder.' Many customers will then move it to the inbox, which trains their provider to trust your messages. See seven traps that stop visitors booking online for other reassurance points.
Common mistakes
- Using a free webmail address as the sender.
- Skipping domain authentication.
- Testing only with one email provider.
- Sending large batches from a brand new domain.
- Never checking spam folders.
- Using a trial sender address for real customers.
Frequently asked questions
Why are my booking confirmation emails going to spam?
Most often the sending domain is not authenticated with SPF, DKIM and DMARC, or the from address is a free webmail address or a placeholder.
Does Crescelo send confirmation and reminder emails?
Yes. Booking confirmations with a private change link, reminders before the appointment and lead alerts are sent by email.
What is the difference between SMTP and Resend?
Resend is an email API service; SMTP is a standard relay you connect to with host, port and credentials. Both need a verified, authenticated sending domain.
Who configures the sending service in Crescelo?
The platform operator configures SMTP or Resend; notification settings for your assistant are in Channels and Integrations.
How do I test delivery?
Send a real booking to several providers, check spam folders and inspect the headers for SPF, DKIM and DMARC passes.
Can I use a free email address as the sender?
It is not recommended. Use an address on your own verified domain.
See the appointment booking feature, lead capture and pricing, and read preventing no-shows with reminders.
Further reading
- Google Search Central: creating helpful, people-first content: What Google looks for in useful pages.
RESPONDE A CADA VISITANTE. RESERVA CITA A QUIEN ESTÁ LISTO.
Instala Crescelo en tu sitio web en 15 minutos
Entrena a tu asistente con tus listas de precios, documentos y condiciones de servicio. Activa respuestas basadas en tus fuentes las 24 horas y reservas de citas en el chat sin solapamientos.