Strange mail list behavior

Hello,

Sorry to spam your mailboxes,

It seems that when I try to post on the list, the message is held,
until I post from the computer I used to subscribe
(gizmotronics.dyndns.org). This even if I change the From header to
 when I post from elsewhere.

Sorry for the inconvenience. If I am doing something stupid, you can
answer me in private.

-- 
Charles Plessy