No longer is it necessary to write letters, address envelopes, buy a stamp and post the letter. The whole process can be done from a computer terminal. Whilst this means that it is possible to have online communication with students, researchers, mentors and classes in real time it also removes the time lag when responding to perceived insulting or angry remarks. Check your upset or anger at the keyboard and use the reply mode with caution. While e-mail has the potential to reach one person or a large number of people quickly, it also has the potential to annoy those people just as quickly.
Few people appreciate junk mail in their mail box and the same applies to e-mail accounts.
Think before you send that e-mail and ask, is it necessary and am I sending it to the right person or persons. E-mail is international, humour often isn't. What you may see as funny or clever may be perceived quite differently by people in other cities, countries or cultures. Use blank spaces between paragraphs. Fill in the subject line.