# Email to SMS: how an email-to-SMS gateway works, when to use it and how to secure it > An email-to-SMS gateway turns an e-mail addressed to a phone number into a text message, so monitoring tools, helpdesks and older systems that can only send e-mail can reach people by SMS. Here is how it works, when it beats an API, and how to lock it down against spoofed mail. - Canonical URL: https://www.broadnet.me/blog/email-to-sms-gateway-guide - Language: en - Last updated: 2026-09-28 - Publisher: BroadNet (https://www.broadnet.me) - Published: 2026-09-28 - Author: BroadNet Editorial Team An email-to-SMS gateway converts an e-mail into a text message: you address the e-mail to the destination phone number at the gateway's domain, the body becomes the SMS, and the gateway sends it through the same A2P route as an API call. It suits systems that can send e-mail but not call an API, such as monitoring tools, helpdesk and ticketing software, and older business applications. Because anyone can forge an e-mail's From address, a safe gateway accepts mail only from allow-listed senders on domains that pass SPF, DKIM and DMARC. ## Key takeaways - Address format: the phone number at the gateway domain, for example @. - The e-mail body becomes the SMS text; keep it short and plain. - Best for alerts from tools that already send e-mail, and for systems without HTTP integration. - Security: allow-list sender addresses and enforce SPF, DKIM and DMARC alignment. - For new applications, the SMS API gives more control and richer error handling. ## How does email to SMS work? 1. Your system sends an e-mail to @, with the number in international format. 2. The gateway checks that the sender is allowed and that the domain passes authentication. 3. It takes the body (and, where supported, instructions in the subject) and builds the SMS. 4. It submits the message on the normal A2P route, with the usual sender-ID rules. 5. The delivery receipt can come back as a reply e-mail to the sender or to a configured address. ## When should you use email to SMS instead of an API? | Situation | Email to SMS | SMS API | |---|---|---| | Monitoring alerts from tools that already page by e-mail | Good fit: point the alert at the gateway | Needs an integration | | Helpdesk or ITSM tools with e-mail output only | Good fit | Needs a custom connector | | Sending from a spreadsheet or mail client occasionally | Workable | Overkill | | Customer-facing OTPs and transactional flows | Not recommended | Yes: faster, with structured errors | | High-volume campaigns | Not recommended | Yes: queuing, throughput and reporting | The rule of thumb: e-mail is the bridge when you cannot change the source system; the [SMS API](https://www.broadnet.me/products/sms-api) is the choice when you can. Our guide on [sending SMS from Python, PHP, Node.js, Java and C#](https://www.broadnet.me/blog/send-sms-api-python-php-nodejs-java-csharp) shows the API side. ## How do you secure an email-to-SMS gateway? E-mail was not designed with sender authentication, so a gateway that accepts any From address lets anyone who knows the format send texts at your cost and under your sender ID. Lock it down: - Allow-list the exact sender addresses per account. - Publish SPF and sign with DKIM on the sending domain, and set a DMARC policy the gateway enforces. - Send from a dedicated address for alerts, not a shared mailbox. - Set spending and rate limits on the account. - Never put passwords, codes or personal data in alert e-mails that become SMS. BroadNet's gateway accepts mail only from allow-listed sender addresses on SPF, DKIM and DMARC-aligned domains, which stops a forged e-mail from triggering a send. See [email deliverability](https://www.broadnet.me/answers/email-deliverability) for how these records work. ## How should you format the e-mail? - Plain text only: HTML, signatures and disclaimers can end up in the SMS or push it over the length. - Put the important part first: the alert name, severity and host fit in the first 160 characters. - Remove reply chains and footers in the sending tool. - Remember the character limits: 160 GSM-7 characters per SMS, 70 in Unicode; see [the SMS character limit](https://www.broadnet.me/answers/sms-character-limit-explained). Example alert: subject "CRITICAL db-01", body "CRITICAL: db-01 disk 95% at 03:12 UTC. Ticket 4821." That is one short SMS the on-call engineer can act on. ## How do you set up email to SMS with BroadNet? Email-to-SMS is a thin layer over the standard BroadNet A2P send, so operator-direct routes, sender-ID enforcement, delivery receipts and audit logs are the same as with the REST API. Setup details, the address format and the supported subject syntax are on the [email-to-SMS developer page](https://www.broadnet.me/developers/email-to-sms). Test access comes from our engineers within one business day of your request. ## Frequently asked questions ### What is an email-to-SMS gateway? A service that turns an e-mail addressed to a phone number into a text message and sends it over the SMS network. ### How do I send an SMS from e-mail? Send the e-mail to the phone number at your provider's gateway domain from an allow-listed address; the body becomes the SMS. ### Is email to SMS secure? Only if the gateway restricts senders. Use an allow-list and enforce SPF, DKIM and DMARC so forged e-mails are rejected. ### Can I receive delivery reports by e-mail? Yes. The delivery receipt can come back as a reply e-mail to the sender or to a configured address. ### Should I use email to SMS for OTP codes? No. Use an SMS or OTP API for codes: it is faster, returns structured errors and supports fallback. ### How long can an email-to-SMS message be? The same as any SMS: 160 GSM-7 characters or 70 Unicode characters per segment, with longer texts split into billed parts. Reviewed 28 September 2026. See our [editorial standards](https://www.broadnet.me/about/editorial-standards).