I followed many of the posts so far about this, and I do understand why an email client will see the relayed messages as Spam. What I wasn't aware of was that the ISP may also see it as spam, making it impossible to send to anyone at a particular domain. Using didyoureadit I sent two emails to myself, each account being on a different ISP. I sent both messages from my same gmail account. Sending was flawless. The first message did work, although Thunderbird acted odd when I opened that message (so much for this being invisible). The second message seemed to vanish in the ether for awhile. The next day a bounced message appeared back at gmail: "Barracuda Spam Firewall to me - 2:34am (8 hours ago) " Even (not!) cooler than that, a view of the didyoureadit email log shows this email is still waiting being opened. Talk about bad design! There is no warning at all about this on their web site, and there is no way I could ask my recipient to turn of his *isp's* spam filters. I return to the didyouread it site. Now I notice there are *no* help files covering any problems, troubleshooting, or spam filters. I would love to have asked someone, but their user support phone number was conspicuously absent. Hmmm. I think their should change their domain name to did-you-think-this-would-really-work?.com