Don't Automate Direct Messages
Some Twitter users set up their Twitter accounts to automatically send a direct message (DM) to each person that follows them. The problem with automated direct messages is that many Twitter users follow thousands of people. Every time a direct message sent, it also sends an e-mail. That means heavy Twitter users can receive avalanches of automated e-mails.
Direct messages should never be automated. Think of it as sending an e-mail to someone (which is what it is). DMs should be personalized.
Don't Send Direct Messages to Someone You Aren't Following
More about Twitter:
I've written a longer tutorial on how to use Twitter, as well as created some Twitter lists that make it easy to find other hostel companies on Twitter:
Here are HostelManagement.com's Twitter feeds: