I searched the tracker and I didn't see anyone else
post an issue like this so...
Using Tiki 1.9.0 final version with Apache, PHP 4.3.9,
MySQL, on Debian stable.
When setting the tracker field "Send copies of all
activity in this tracker to this e-mail address:" or
when monitoring a tracker - all outgoing emails from
the tracker entries (first or mods) fail with the
This message was created automatically by mail delivery
A message that you sent could not be delivered to one
or more of its
recipients. This is a permanent error. The following
SMTP error from remote mailer after end of data:
host mr-int.wpafb.af.mil [188.8.131.52]: 550
Requested action not taken:
Nonstandard SMTP line terminator.
Emails from other capabilities like monitoring wiki
page changes works perfectly.