I had similar problems when I didn't use an smtp while sending mail to certain adresses, only I use postfix. My error was:
(conversation with columbo.hvu.nl[145.89.50.200] timed out while sending end of data -- message may be sent more than once) However, this turned out to be a router problem, not a Postfix problem. So you might have the same problem. Have a look at http://www.postfix.org and go to the FAQ. The exact description is at the item "Mail fails with timeout or lost connection". If you have this problem, you can't solve it yourself because it's caused by some router fragmenting packets it should not fragment. Hth, Wouter -- Linux duckman 2.2.14 #1 Wed Jan 5 14:45:16 CET 2000 i586 unknown 10:11am up 2 days, 21:09, 1 user, load average: 0.02, 0.04, 0.00