CORE-795 is fixed for 3.0.4. To patch yourself update /components/email/email.php lines 260-276:
from:
$body_text = null;
foreach ($this->message->getChildren() as $child) {
if ($child->getContentType() == "text/plain")
$body_text = $child->getBody();
}
$vars = array_merge($vars,
array(
'to_address'=>implode(',', array_keys((array)$this->message->getTo())),
'from_address'=>implode(',', array_keys((array)$this->message->getFrom())),
'from_name'=>implode(',', array_values((array)$this->message->getFrom())),
'cc_address'=>$cc_address,
'subject'=>$this->message->getSubject(),
'body_text'=>($body_text),
'body_html'=>($this->message->getContentType() != 'text/plain' ? $this->message->getBody() : null)
)
);
to:
$body_text = null;
$body_html = null;
foreach ($this->message->getChildren() as $child) {
if ($child->getContentType() == "text/plain")
$body_text = $child->getBody();
}
if ($body_text === null)
$body_text = $this->message->getBody();
else
$body_html = $this->message->getBody();
$vars = array_merge($vars,
array(
'to_address'=>implode(',', array_keys((array)$this->message->getTo())),
'from_address'=>implode(',', array_keys((array)$this->message->getFrom())),
'from_name'=>implode(',', array_values((array)$this->message->getFrom())),
'cc_address'=>$cc_address,
'subject'=>$this->message->getSubject(),
'body_text'=>$body_text,
'body_html'=>$body_html
)
);