What is SMS SMTP?

SMS SMTP or Short Message Service Simple Mail Transfer Protocol is a messaging protocol that allows sending SMS text messages via SMTP email gateways. It bridges the difference between the protocols that manage SMS messages and email.

What is SMS SMTP?

How SMS SMTP Works

SMS SMTP takes advantage of the similar client-server architecture in both SMS and email to convert SMS messages into MIME email format. This allows using an email client or app to send SMS. Here is a quick overview of the SMS SMTP process:

  • A user composes an SMS message through an email client or web app that supports SMTP protocol.
  • The client/app connects to an SMS gateway using SMTP instead of regular email SMTP servers.
  • The SMS gateway provider converts the email into SMS format per the SMTP to SMS protocol mapping.
  • The SMS is routed through the cellular network as a native SMS to the destination mobile phone.

So in summary, SMS SMTP allows sending SMS via SMTP by leveraging gateways that interconnect between both protocols.

SMTP to SMS Protocol Mapping

The core protocols for email and SMS share some common elements that enable SMS SMTP gateways to convert between them:

SMTP envelope sender Sender mobile number
SMTP envelope recipient Recipient mobile number
SMTP mail body SMS message text

In essence, key email metadata like envelop sender/recipient align to SMS sender/receiver. And the email body maps to the SMS text payload.

SMTP also specifies the transmission specifics through headers like SMTP auth, TLS, etc. The gateways handle any protocol differences behind the scenes.

Key Benefits of SMS SMTP

Some benefits of sending SMS messages through SMTP include:

  • Leverage email clients – Users can stick to familiar email tools without learning special SMS software.
  • Email features – Get email conveniences like contacts, calendars, attachments, drafting, etc. when sending SMS.
  • Easier integration – SMTP is a universal standard that is easier to connect to other systems and apps than SMS APIs.
  • Analytics – Email platforms provide tracking and analytics not as readily available for SMS messaging.

So in summary, SMS SMTP bridges the messaging realms of SMS and email for easier access to benefits across both systems.

How to Send SMS via SMTP

Here is an overview of how to send SMS messages using SMTP:

  1. Select SMS SMTP provider – Choose an SMS gateway provider like Twilio, Infobip, etc. that offers an SMTP interface. They will assign you an SMTP mail server hostname and credentials.
  2. Configure email client – Set up your preferred email client, webmail, or app to connect to your SMS provider’s SMTP server instead of normal email SMTP. Authenticate via the credentials provided.
  3. Compose email message
  • Enter phone number as recipient in proper numeric format.
  • Write SMS as you would an email body.
  • Set sender to your allocated virtual number or sender ID.
  1. Send SMS – When you hit send, the client submits the message to the SMS gateway over SMTP. They handle converting it to SMS format and pushing it to the destination operator and device.

And that’s it! The SMS provider and mobile networks do the heavy lifting after your SMTP client delivers the message.

Top SMS SMTP Gateways

Some top SMS SMTP gateways include:

  • Twilio – Cloud communications platform with feature-rich SMTP SMS gateway and APIs.
  • Infobip – Specialized global SMS provider with SMTP and broad messaging options.
  • Amazon SNS – AWS messaging service supporting SMS SMTP integrations.
  • TeleSign – Enterprise-grade messaging solutions with international reach.
  • Twilio SendGrid – Popular email platform now offering SMS capabilities.

When choosing a provider, evaluate delivery success rates, routes and coverage, two-way messaging support, reliability, scalability, and costs based on your messaging needs.

Building SMS SMTP Integrations

SMTP’s universality makes SMS easily integrable into diverse backend systems and apps via the supported gateways above:

Email clients

Configure native SMTP settings or extensions in clients like:

  • Gmail
  • Outlook
  • Apple Mail
  • Thunderbird

Web frameworks

Expose SMTP SMS functionality in code via libraries like:

  • PHP Mailer
  • Python Django
  • Nodemailer
  • Java Mail
  • Ruby Mail

CRM software

Embed SMTP SMS capabilities into platforms like:

  • Salesforce
  • Oracle CX Cloud
  • Zoho
  • HubSpot
  • Zendesk

This allows enabling notifications, reminders, alerts, 2FA, and other workflows via SMS across sales, service, marketing, or collaboration systems.

Typical Use Cases

Common SMS SMTP usage scenarios include:

  • 2FA/MFA – Sending one-time passcodes for multi-factor user authentication via email clients.
  • Notifications & alerts – Enabling SMS alerts for services monitoring, sales/pipeline updates, SLA violation notices, appointment reminders, shipping notifications and more
  • Marketing – Sending SMS campaigns for lead gen offers, event promotions, cart abandonment recapture, loyalty programs etc.
  • Customer service – Automating order/case updates, feedback requests, detractor re-engagement and other CX communication workflows.
  • Chatbots – Using natural language SMS capabilities for conversational alerts, answers, transactional use cases like bill pay etc.
  • Internal systems – Integrating SMS into business apps for multi-channel internal comms across sales, HR, facilities, IT help desk, network monitoring systems etc.

As the examples illustrate, nearly any external- or internal-facing system can integrate SMS SMTP for more streamlined and meaningful stakeholder comms and engagement.

Key Takeaways

  • SMS SMTP enables sending SMS texts via email clients using SMTP gateways to interconnect the protocols.
  • It provides user convenience by avoiding specialized SMS software and allowing use of email tools.
  • Integration is simplified by tapping into universal SMTP messaging standard.
  • Use cases span across marketing, CX, integration with CRM/business systems, and more.
  • Leading providers make scalable integrations feasible for enterprises.

So in summary, SMS SMTP unlocks the power of email infrastructure and software ecosystems for streamlined, richer SMS capabilities.


SMS SMTP bridges SMS and email protocols through gateways that translate messages between the systems. This allows conveying SMS texts via familiar email tools and backends. Enterprises can gain user, CX, and operational benefits by incorporating SMS SMTP in their tech stacks for more impactful mobile messaging. As mobility and messaging grow, so too will the interoperability enabled by protocols like SMTP for SMS.

Frequently Asked Questions

What is an SMTP SMS gateway?
An SMTP SMS gateway is an intermediary server that enables sending native SMS texts through the SMTP mail protocol. It seamlessly converts messages from email clients into SMS format and back via built-in interoperability.

How do I send SMS text messages through Gmail?
First set up an SMS SMTP gateway service account and configure Gmail SMTP settings to route through the SMS provider SMTP server instead of the default Google mail server. Compose emails with phone numbers as recipients, SMS body content, and activate send. The gateway will convert the messages automatically from email to SMS format for delivery.

Can I send SMS online without a phone?
Yes, through SMS SMTP gateways. By using a web mail client or web app that connects via SMTP to an SMS provider gateway, you can send SMS without a mobile device. The gateway handles translating the messages to SMS protocol and transmitting to recipients.

Is SMS SMTP free?
No. Leading SMS SMTP gateways like Twilio, Infobib, Amazon SNS etc. offer free trials but charge per message sent for actual usage. Cost depends on volume discounts, message types, integrations and other add-ons. Still, costs remain affordable relative to specialized SMS software tools.

How can I integrate SMS into Salesforce?
Configure Salesforce email actions, Lightning flows, process builders, triggers or 3rd party add-ons to route through an SMS gateway SMTP server instead of the default SF mail server when sending notifications. Recipient phone numbers are placed in customer records. Enable 2FA using SMS MFA apps.

Can I receive as well as send SMS through SMTP?
Select SMS gateways offer two-way messaging via supported email clients using advanced routing techniques like inbound MX records in DNS, dedicated inbound numbers, or email plugins reading SMS webhook payloads. This enables SMS autoresponders, chatbots, support queues and other CX workflows.

How can I track SMTP SMS deliverability?
Use email tracking apps compatible with SMS SMTP providers to trace metrics like send confirmations, delivery receipts, replies, geolocation and more. Many SMS gateways have built-in historical and real-time dashboards showing delivery reports, latency, failover details etc. Some integrate with big data and analytics tools too.

What’s the difference between SMPP and SMTP for SMS?
SMPP or Short Message Peer-to-Peer is another popular protocol besides SMTP for application-to-person (A2P) SMS messaging. SMPP offers more advanced SMS routing options best suited for high-volume SMS providers. SMTP remains simpler and more universal for easy integration across email ecosystems and GUIs, albeit less optimized for solely dedicated SMS infrastructure.

Can I export SMS delivery reports?
Yes. SMS SMTP platforms usually provide API access to message logs that can integrate with business intelligence tools. Email apps may enable exporting contact engagement tracking. Many gateways also have CSV/PDF exports of historical SMS data for consumption across data visualization, modeling and analytics systems enabling better metrics.

Which is better SMTP or HTTP API for sending bulk SMS?
For highest volume bulk SMS like marketing campaigns, dedicated HTTP APIs tend to offer more control, customization and throughput efficiency. But for lower to mid-volume use cases like CX workflows, SMTP achieves sufficient scale with lots of backend flexibility. As SMS SMTP evolves with 5G adoption, SMTP will close the scale gap further.
I hope this draft article provides a comprehensive overview of SMS SMTP and how it enables streamlined SMS capabilities. Please let me know if you need any clarification or have additional suggestions to expand the content. I’m happy to refine further details as needed!


Leave a Comment