In case anyone is interested, my problem with sending to the list from gmail is actually like so:

- I send to the list - it's actually delivered to the mail expander fine.

- Expander sends the mail back to me (and presumably to everyone else)

- Gmail decides this incoming mail is suspicious.  That's fair since it has a gmail message id and comes from my own email address.

- GMail quarantines the inbound message

- But Gmail quarantine admin page shows this quarantined mail as "Outbound".  That is wrong, it's actually inbound.

Cue lots of confusion.

Seems to fix I need to whitelist the mailman 175.45.17.210 address in my gmail advanced setup.

Holding thumbs.

Steve