That's because you're posting in HTML to the list (albeit with a plain text version as well). You should be able to turn this off and post without being held for moderation.
Ok I'm using web based gmail at the mo, hit plain text and voila BUT I'm going to try replying from my Google phone too as I think that may be the problem, the official google mail client seems pretty optionLESS so wondering whether that by default mails out in HTML format.. we shall see o.O
Cheers (and sorry to spam your topic Chris)