The email is already an Html email, it contains text portion plus Html
source code. It happened that the first element in the message is
anchor element, which its href attribute's content appear in the
Desktop Alert.

href attribute is part of Html soruce code and suppose not to be
displayed if message already contains text portion. Back to the
problem, Desktop Alert insist to display href and drops any other
defiend attributes, for example:
a style="somestyle" title="title" href="somelink"Link/a .. the
following will be shown href="somelink".