An anonymous reader writes: I run an MTA on my personal e-mail server, and I'm not listed on any blacklists for SPAM that I'm aware of. When I send e-mail to certain URLs, though, it frequently never reaches the intended recipient. Yahoo seems to be notorious for labelling almost anything sent as spam unless and until the recipient adds my e-mail address as a whitelisted entry. Others also seem to get dropped without any response. Checking the maillog, I can see where it's accepted by the MX of the recipient; what else can I do?