When you create an email account for online chat purposes, select a user name that is some portion of your name. Less mature users will often select cutesy names or otherwise try to completely obscure their identity.

Fill in the email profile with general information. Never provide detailed information such as street names, phone numbers, schools (if you aren't in college or older), place of employment, etc. It is generally OK to provide age (if over 21), gender, your state and interests.

Narrow your focus. The more that an online group shares a common interest, the more likely the maturity level may be higher.

Join a few groups and read the archives of the group. Read the current message exchanges and note how various people communicate. Often it is possible to instant message or email someone whose writing style seems mature and inquire about other groups that may be even better. Networking within groups is a good way to discover groups with good reputations for mature discussions.

Create a blog and add people that you know in real life as friends. Blog communities often have internal groups and interests allowing for access through those same shared interests. By reading the message traffic, it will become clear who is mature and who isn't. Block those whose message style doesn't meet your needs.