This habit is really one of Stephen Covey's seven habits. The notion here is to keep learning and to hone the tools that you have so that they are ready to use when you need them. Many users are simply unaware of helpful features readily available in their programs. Becoming a highly effective e-mail user requires that you update your skills regularly, experiment with software features and devote yourself to continuous learning and improvement. Seek training for yourself and others on a regular basis.
Many people spend a good portion of their days only in e-mail.
You might find that a mini-session on using rules, managing folders or creating groups will be surprisingly well attended and can be repeated from time to time. E-mail raises issues on a regular basis. You will want to keep apprised of virus and security issues. Encryption is a growing and important issue. Again, a great resource on a variety of e-mail issues is Jerry Lawson's excellent The Complete Internet Handbook for Lawyers.