Sometimes, a duplicate content-type header is inserted in the Mail sent through an HTML-mail object through AWA.
Depending on the server mail settings, the mail can be rejected as this is not RFC compatible.
Release : 12.2 + 12.3
Component : AUTOMATION ENGINE
Special characters used in the mail (using Umlaut - ä ö ü).
Workaround : do no use Umlaut (ä ö ü) in the mail object.
Will be fixed in future release