Capitalization would follow written rules. If replying to business communication, be guided by their style. In most cases, they have better things to do. Email from home passes though a server shared by millions of individual emails, but the theoretical risk remains. Even a deleted email probably still exists on a server somewhere, and could be retrieved if required - such emails have been used as evidence in court cases.
Most internet users receive unwanted mail.
Many sites ask you for your email address, and may sell on the lsts they compile. Others may scour newsgroups and mailing lists, scavenging all users. Flaming has come to refer to almost any mail insult. The art has long since disappeared, and flame wars can be abusive, aggressive and unpleasant exchanges in newsgroups, mailing lists and email. Find out more .