This essay is not about e-mailing your clients but about "e-mail clients" -- that is, software that supports your receiving e-mail that is not dependent on membership in a particular service or institution -- so that you can keep your e-mail address after graduation, changing jobs, chaning ISPs, etc.
The following list provides contact for free e-mail clients :
The benefit to being John@Yahoo.com is that if you are John Doe at Harvard, then become John Doe at Cal State Chico, then become John Doe at Jones Day, then become John Doe on AOL, then John Doe on SWBell, then John Doe on new client ISP service ... you remain John@Yahoo.com for all your e-mail throughout all of that time.
Of course the services may merge, go out of business, change names, etc. Nothing is permanent or certain on the internet.
adrr.com remains available for $25.00 a year if these services do not meet your needs. Visit http://adrr.com/join.htm for details.
If you want to maintain an on-line forum, one of these providers may be just what you need. Free, powerfull, fast, and requires no web space account.