are we talking about the test message sent during account verification?
if so, it's a well known Outlook bug since... well, since Outlook exists (see https://wiki.contribs.org/Email#Outlook_test_message_doesn.27t_come_through)you can disable the header's check (see the same page, some rows below)
This shouldn't be needed anymore with sme 9.2 as the date header is now disabled by default
yes.. outlook sends a message with no "date" header in its testin SME9.2, with the new qpsmtpd, many things are changed (see https://bugs.contribs.org/show_bug.cgi?id=9773)
Hey HF, see that bug for comment 34 re restart of qpsmtpd, I know I am telling you the obvious, BUT, you never know