Email Groups and Replies

Hi all, So, I was going to make a mailing list so we can send an email to allstaff@domain.com but having looked at the mailing list set up, it seems quite complex for me. So, I've made an email account called allstaff@domain.com and then put a rule on it via cPanel to redistribute any email to that email address to the staff and added their emails. What I've noticed though is something a bit strange. I emailed all our staff from my own email address but send the email to the allstaff@domain.com email address. People have got it which is great but when they reply, surely their reply would be to me as the email came from me? Insead it seems to reply to the allstaff@domain.com email address even though it wasn't sent from that. Does anyone have any ideas? Or could anyone help me set it up as a mailing list so this works for us? Thanks in advance! Ben