Integration of an SMS and email API
The product decides what goes out, not the emailing tool
We wire transactional email, SMS and telephony to your business events. Invoice paid, code, status: the message leaves from a state, not from a mailbox.
- Messaging connectors in production
- transactional scoped
- GDPR log
What is an SMS and email API and when should you have it integrated?
An SMS, email or telephony API lets your application send a message, verify a number, follow up a customer or have an agent pick up, and track delivery. Off-the-shelf plugins cover a simple send. You have the integration built when the OTP must be idempotent, when a hard bounce must cut the address, when the French legal sending window applies in code, or when the call should leave from the customer record rather than a softphone on the side.
The SMS, email and telephony APIs we integrate
Twilio
SMS, OTP, WhatsApp and programmable voice, with delivery tracking.
Brevo
Transactional email and SMS in a French account, templates included.
Ringover
Agent telephony: click-to-call, screen pop, call log.
Mailjet
High-volume email sending, French vendor, no telephony building block.
Resend
The modern alternative for transactional email, to wire into the product.
What still leaves from a mailbox
The sending tool sends. Until the event lives in a state, OTP, invoice and unsubscribe stay artisanal.
We do not know if the SMS arrived
Delivery status comes back into your product. A failure triggers another channel or an alert, not silence.
We keep writing to dead addresses
A hard bounce cuts the address on the first rejection. Deliverability is protected in the connector, not in a report read too late.
The OTP goes out twice, or never
Every create carries an idempotency key. A replay does not produce a second SMS, a network incident does not leave the user without a code.
Agents type the number by hand
Click-to-call from the record, screen pop on ring, log without typing. Telephony lives in the business, not beside it.
What each communication API actually involves
Brevo
Email + SMS FRTransactional email and SMS in a French account, with templates and deliverability webhooks. Useful when marketing and transactional should stay in the same tool, and when a hard bounce must cut the address on the first rejection. Contact sync is scoped so consent is not overwritten.
- Transactional email and SMS
- Hard bounce cut
- Contacts synced without overwriting consent
Mailjet
High-volume emailA French high-volume email vendor, with no telephony building block. No detailed sheet here: the integration is judged on templates, deliverability webhooks and bounce handling, not on an announced catalogue of routes.
- High-volume sending
- Deliverability tracked
- Scope settled at scoping
Resend
Modern emailA modern option for transactional email, useful when the product team wants a simple API rather than a marketing suite. A short page by design: scoping fixes the events to send, the domain and bounce tracking. No invented routes.
- Transactional email in the product
- Domain and bounces scoped
- Lightweight alternative
Ringover
Agent telephonyA French operator that equips humans who make calls: handsets, supervision, click-to-call, screen pop. The API is used to graft that telephony onto the business software. Throughput is tight and the call identifier is not a primary key: that is designed in the connector, not after the fact.
- Click-to-call from the record
- Screen pop on ring
- Log without a typed report
Twilio
SMS, OTP, voiceThe programmable operator: SMS, Verify for OTP, WhatsApp, voice. The useful cluster is generic (SMS API, send-SMS API) more than the brand. The integration is judged on idempotency, delivery tracking and the French legal window applied in code, not on the first POST Messages.
- SMS, OTP and WhatsApp in the product
- Delivery status logged
- Legal window in code
Four sends born from an event
OTP and codes from the account
The code is born in the application, sending is a channel. No more SMS typed in a side tool.
Billing transactional
Issued, reminded, paid: mails follow state. Marketing stays in the ESP, transactional in the product.
Voice or SMS fallback
When email bounces, a second channel. The account is updated, not only the campaign.
Bounce that corrects the record
A hard bounce invalidates the address. The DPO has a log, sales no longer writes into the void.
Product, ops, DPO, finance: the channel has a cost
We do not “plug Brevo in”. We set the event taxonomy and sender identity.
Product owns the event
“invoice.paid” is not a marketing template. We freeze it, then we route it.
Ops see the bounces
Deliverability becomes a signal again. A burning domain shows before blacklisting.
The DPO has a send log
Who received what, on which basis, until when. This is not a campaign export.
Finance caps SMS
A2P cost is designed. We set the guards, not a month-end surprise.
What we have shipped, and why it transfers here
The method a send channel forces
Transactional vs marketing
Split of flows, domains, opt-in bases.
Deliverable: regime splitSender identity
Authenticated domain, sender IDs, environments.
Deliverable: sending identityBounce handling
Bounce classes, record update, reputation alert.
Deliverable: bounce ruleGDPR log
Log, retention, controller.
Deliverable: send logWhat nobody tells you before you sign
A send without tracking does not exist
Without a status webhook, you do not know if the message arrived. The connector treats delivery as a nominal case, not as an optional report.
The legal window is coded, it is not documented
A marketing SMS outside the slot is a risk, not an oversight. The rule lives in the connector, with an explicit refusal rather than a send “we will see”.
Idempotency is not a luxury on OTP
A double send is expensive and confuses the user. Every create carries a key, and a replay resumes the same message.
Agent telephony and programmable voice do not mix
Ringover equips humans. Twilio makes an application place calls. Gluing them without saying so produces two logs and zero call truth.
What we measure on an SMS and email project
SMS and email API integration: your questions
Three steps. First freeze the events that send (OTP, notification, reminder) and the legal window that applies. Then build a connector on the server side, with an idempotency key on every create, secrets isolated and handling of status webhooks. Finally cut failures: bounce, insufficient credit, outside the slot. The sensitive part is never the send call, it is tracking and replay.
It depends on the channels and the edge cases. A Twilio OTP costs far less than a full email + SMS + agent telephony chain. Deliverability, consent and the log weigh as much as the first send. We scope the perimeter up front and give a firm estimate.
Twilio makes an application send and call: SMS, OTP, WhatsApp, programmable voice. Brevo sends transactional email and SMS from a French account, templates included. Ringover equips human agents: handsets, click-to-call, screen pop. They are often combined. The right scheme is decided on who sends, and who picks up.
Yes, and it is common: a transactional channel, a marketing channel, agent telephony. The difficulty is keeping a single truth on the product side. We put an internal message model, independent of the provider, before it reaches your business logic. Without that layer, each channel duplicates consent and the log.
By treating the webhook as a business event. A hard bounce cuts the address, a soft bounce is retried according to a policy, a spam complaint leaves the list. Retrying a dead address “to see” destroys the domain's reputation. That policy is coded at scoping, with your product team, not in a dashboard read after the fact.
Which events really need to go out?
30 minutes to split transactional and marketing, set sender identity and the log the DPO expects.
Discuss my SMS and email project