All email has a return email address.

Uh, yeah. When I clicked "reply" to the message you sent me, here's the address thar was inserted into the "Send to" block:

gardenweb_user@gardenweb.com (that's it, in total)

The header on your message:

From: gardenweb_user@gardenweb.com (giventake)

I (think) you chose to receive a email from a posting to a question, you posted on 'garden-web",

It depends on whether or not your user profile includes the permit email option. If you do permit email then your member page will have a send-me-an-email link and your message will include an address to reply to. If not the email will just be sent from the garden web site with the message included in it but wont give the senders address.

giventake is right that the email will have a return address, but it wont be the senders it will just be the garden web mail box.