I think you'll find that gmail silently drop such requests. Some email providers swallow them on receipt, that is, they don't forward them on to their users. Send me one from each of your accounts to me at ''xenos at gmx.co.uk'' if you'd like me to see if you are successfully sending them out. Then we can see if the responses make it back to you. Replying to a "Read receipt" is of course optional on the part of the recipient. DSN is not often supported these days; there is a belief that it simplifies the task of identifying working and active email accounts, which might be helpful to spammers.