E-rager: omfgNOOBSTFUKKPLXEZPKGFGTHXNOOBFAG. U SUK NOOB GG. E-RAGE
Random guy: *silent*
Since email is unable to convey facial-expressions, unable to fully-convey emotive states or the status of the writer (ie tired, sick, depressed), is not interactive face-to-face dialog, and tends to be hastily-written, these misunderstandings via email are frequently based entirely upon mis-communication rather than truthful intent.
Term coined by Louise Doncaster circa 2003.