When you respond to a volunteer's message by e-mail, rather than by using VSys itself, VSys doesn't normally "know" about your response and can't track the conversation. To be able to send e-mails to your volunteers from your regular e-mail account and have VSys track them,
Under these circumstances, when VSys sees an e-mail in this account, it assumes that it's from a staff member and to a volunteer. It will look at who the e-mail is being sent to, rather than from, in order to tie it to a volunteer's profile.