DKIM is driving me nuts

[John Levine]

In article <CAFsnNZ+qeK+M1PPFns59wDeH_Y+-3VDmkwN-iZAEU7qcHS8oRA at mail.gmail.com> you write:
>Something is different between using Mail/mailx and using Thunderbird,
>and I've given up trying to figure out what.

Thunderbird includes all the required headers, mailx doesn't so
sendmail has to add some, probably date and message-id.

Please see my previous message which told you how to fix it.

R's,
John

PS: I have to agree with other people, if this is too hard to figure out,
it's time to give up and pay someone else to manage your mail.