getting strange Characters in From and Subject headers

Recently I have been getting messages with From and Subject similar to the following :

ÿþÿþR <simeonisms.lapje@down-town-army.com>
ÿþÿþD

What causes this ?

Messages like this appears in the junk mail folder which is good but is there a way to trash them before it even gets into the junk mail box ? I tried adding filter rules at the Comcast web mail settings but does not seem to eliminate them at all . I am using Outlook 2013 as email client and Comcast is my provider.

Any ideas ? Tks

The headers seem to be variations of ÿþ with added characters so I used ÿþ* in my filter. It worked for a while , then last week it stopped working.