Tilmann: Yes, I checked for leading and tailing spaces in group names, the error is repeated in different groups, and the error message is the same, no matter the groups:
Error: ns_sendmail failed: Expected a 250 status line; got:
501 <notification-Re: test1 mailto:SubGroupTestOnly@mail.zedat.fu-berlin.de>>: "@" or "." expected after "notification-Re"^M
Randy: I do indeed remember the earlier post and am using that patch in sendmail.tcl, so the relevant lines there now read:
# _ns_smtp_send $wfp "HELO AOLserver [ns_info hostname]" $timeout
#changed the above to the following
_ns_smtp_send $wfp "HELO [ns_info hostname]" $timeout