Yes,
It would have to be done using server side code. Since it is easy to do in ASP.NET VB or C# I'll demonstrate how.
Assume when the visitor enters the email address it is stored in a database and you retrieve it using the appropriate driver.
VB. 2k5
Sub sendMail(emailAddress)
Dim oSmtp As New System.Net.Mail.SmtpClient("smtp host", port)
Dim oMessage As New System.Net.MailMessage
With oMessage.To.Add(New System.Net.Mail.MailAddress(emailAddress)
.From = new System.Net.Mail.MailAddress("sender@me.com")
.Subject = "Enter Subject"
.Body = "Enter Message Body Here"
End With
oSmtp.Send(oMessage)
End Sub
If you use authentication credentials for your outbound smtp before you send insert:
oSmtp.UseDefaultCredentials = False
Dim myCreds As New System.Net.Mail.Credentials("username", "password")
oSmtp.Credentials = myCreds
You can also enable SSL.
.NET 1.1 is much different and inferior so if you do use ASP use .NET 2.0.
I don't know how to do it in classic ASP but it is also an alternative.
Try PHP too.