Comma at end of To:

[Ned Slider]

Hi List,

I noticed in a spam mail today the To: line ended in a comma:
To: u...@example.com,

and always being on the lookout for potential new rules decided to 
investigate.

Grepping my spam archive I see a small number of matches, but I can't 
find any examples in ham.

Here's a quick and dirty rule:

header          NSL_TO_ENDS_COMMA               To =~ /,$/
describe                NSL_TO_ENDS_COMMA               To: ends with a comma
score           NSL_TO_ENDS_COMMA               0.001

Does anyone else see this?