While the word is getting out, a very handy feature of many mail servers is the ability to send text messages is still surprisingly not well known. One caveat is that the service provider of the recipient has to be known – not a problem for a lot of applications where the user can provide details.

It’s as simple as sending an email to 888888888@text.server.tld, where 8888888888 is the mobile number and text.server.tld is the carrier’s text server. A decent list can be found here: http://www.mutube.com/projects/open-email-to-sms/gateway-list/ (I’ve used a couple on that list and can confirm they’re valid – obviously I haven’t tried them all).

The PHP could be as simple as: