strange think with 'mail()'

Hy leuts i got a strange problem and hope someone knows a solution or a hint i send a mail in a absenden.php3 like this: mail("kpa@2000pm.de","subjekt","inhalt", "Content-Type: text/html\nFrom: <kpa@2000pm.de>"); the mail reaches me, is readable, but on the next time i start netscape its GONE ? I tryed some other header pieces, but all get the same effekt. does anyone know a reason ? i think the code is quite simple - maybe a problem with senmail? i hope for answers befor my brain goes to the same place where my mails go thanks