[lxgr]

Basically every business/marketing email you receive works like this: Every link you click is personalized and tells the sender that it was you reacting to their message (and from where as well, thanks to GeoIP).

I can see the point in wanting to know whether your messages are reaching your target audience (or somebody else), but I don't really understand who would want to get that via SMS instead of via e.g. email? Email would be much cheaper.