How to Send SMS via Email: Simple Guide

Of course, sending an SMS via an attached phone or GSM modem using AT commands in PDU mode is fun. Sometimes you just want to send a plain text message from your application and you don’t want to bother with phones, SIM cards, data plans, PDU mode and so on.

In these cases, the easiest solution would be to use an SMTP to SMS gateway. SMTP is the protocol used to send an email (Simple Mail Transfer Protocol). What such a gateway does:

• is receive an email
• look at the intended recipient
• figure out a phone-number from/for that recipient
• send the text of the email as an SMS to the recipient’s phone

You could send an SMS message this way using any SMTP library (they come with .NET, JDK and many open source libraries are available to do this from C or C++).

There is a really simple way to test this: just send an email from your email client.

Of course there are some limitations:

• The originator will be some service number, but won’t tell you anything about the sender. Typically something like “From: <source-email-address>” will be inserted in the SMS to give you a clue.
• If your email is too big, it will be truncated at some arbitrary point (160 characters less than the space needed for the originator’s email address).
• You can’t send anything fancy like WAP push, EMS, etc, just plain text.
• Not all mobile operators have such a gateway, so you can’t reach all recipients this way.
• Because of billing and spamming reasons, the recipient will have to opt-in to receive SMS messages via email this way.

Below is a table of mobile operators and the email address format to use to send to one of their subscribers. Replace <n> in the email address with the phone number.

This list is extracted from the Quick SMS WordPress Plug-in developed by Martin Fitzpartick, which is make available under the GPL and BSD open source licenses.