Twitter is increasingly used by companies to maintain and quick contacts “informal” with its network of clients. As shown, An example: The sales manager in Spain for your Amazon Web Services AWS distributed (Amazon Web Services) you chose Twitter as fast channel of communication and “open conversation” with customers.
The advantages are manifold: Twitter is fast, viral somewhat, free, open and easy to use. Whenever there is more present on mobile phones, and lets you communicate with friends open, customers or suppliers.
If you have an account on twitter, Just visit the profile of your customer / supplier and “follow”. From there you will enter your “timeline” twitter short messages to write that person / company.
Twitter does not replace email, but complements it perfectly as an alternative means of mass communication, more informal and close.