This could not be a case of black or white - of absolute good or bad. SMS lingo too is an evolution of language - of communication. Although a few purists would be objecting to it, but they ignore the fact that even the language in present form has evolved from a past form and was not acceptable to many. So, SMS, if used properly - as communication between those who understand the common words between them - is a perfect medium of communication. But in business usage, especially with those from other cultures, a formal usage and tone always yields the best results.