No one knows your gender, age color, religion or other characteristics that lead to prejudice and bias. There's a place for everything. Geographic location isn't much of an issue on the Internet. You can be searching a library's database in London one minute, and five minutes later log on to a computer in Hong Kong. Give back to the community by providing free services and information and by fostering exchange of ideas.
Some service providers have rules against sending commercial-type messages.
Use the same courtesy as you would extend someone you are having a phone conversation with. Flaming occurs when you send a message that provokes an angry, and often nasty, response. When others join in, a full-fledged flamefest ensues. Use the same rules regarding good grammar, punctuation and word choice as you would for any written communication. Some Email systems occasionally become plagued with electronic versions of chain letters.