In many ways, the recent generational evolution of the English language is rapidly changing our use of writing and even speaking. I say generational because people younger than 30 are much more likely to rely quite heavily on text messages, which uses shortcuts and many TLA's (three letter acronyms, e.g., LOL) in familial and social texts.
However, the professional world is the professional world. The use of these shortcuts reflect poor grammar, and spelling. It also shows a certain lack of care and, therefore, a lack of professional consideration: you could not take the time to correctly spell out entire words.
At the end of the day, business is business. A sign that you are working with another professional, and that you, yourself are truly professional, means avoid shortcuts at all costs. If you are business friends or partners, it is easy to be casual. However, it is not always known what the other person expects from you. If you are always professional, you will stand out. If you are sloppy or lazy, you will be known for that.