> echo smtp.comcast.net |ndb/dnsquery >/dev/null Yep, this is what I do too, I followed it through smtp(8) a while ago and came to the conclussion it was a caching problem in dns(8).
looking at /sys/src/cmd/upas/smtp/mxdial.c:163 smtp looks up "smtp.comcast.net mx" but receives "dns failure" and gives up. dns should reply "resource does not exist" which would prompt smtp to retry with "smtp.comcast.net ip" which will succeed. If you force the "smtp.comcast.net ip" into dns's cache using the manual query above then it replies "resource does not exist" correctly and smtp completes as it should. After some time the entry ages out of the cache and the problem reappears. I used ndb/dnsdebug to prove that it was not a dns config problem and put it on my To-Do list, where it has gathered dust. A little more info, but no fix - only the same old bodge, sorry -Steve
