JP and the mailing list -- "reply all" behavior

[Kenneth Brody]

Can anyone explain this behavior that I see regarding JP's posts to the list?

Normally, when I reply to a post, I use "reply all", which sends the message 
"to" the original poster, and "cc"s the list.

However, with JP, and only JP as far as I see, "reply all" sends the reply 
only "to" the list.  I have checked the message headers and I don't see 
anything different in his posts than anyone else's to account for this.

Any ideas?

(Note: I use Thunderbird for e-mail.)

-- 
Kenneth Brody