Hi Lieven,
I assume some party asked for extended SMTP. It is strange indeed, a Domino server should accept it. What I find very strange is that you get Failure Reports even with a reason 250 only. What version of Domino do you have?
Other victims of the same problem:
http://www-10.lotus.com/ldd/nd6forum.nsf/869c7412fe5d56b7852569fa007826e3/8122f605f93a26d185256f46005c0966?OpenDocumenthttp://www-10.lotus.com/ldd/46dom.nsf/55c38d716d632d9b8525689b005ba1c0/9b582a1ad12a312585256aaa004626dc?OpenDocumentThe 2nd is the most promising: it tell you to look deeper in the DFR, for there may be a MIME-section with more information that isn't shown by the Notes client. Could you check that??
Sjef