in the old days, lvl 50 parties do almost same exp( about 5-10% less exp per monster) with 6 people in it.
overkilling a monster still yields a bit more exp.
it was a dumb idea to use email as login. way back in warpportal, you can create 4 accounts per email. so that it wont be necesary for email addresses to leak out of 2 decades old tech.