It was originally thought these were AWS spam safeguards. Two things actually happened when the server moved to AWS: (1) Mailman was upgraded from version 2 to 3, and Mailman 3 never implemented MM2's cross-posting dedup — hence the duplicate copies; (2) outbound mail started relaying through Amazon SES, which requires the From address to be @ceph.io, so the "First Last via list" rewrite that previously applied only to a few strict-DMARC senders (gmail, etc.) started applying to every message. Both are now fixed with custom Mailman plugins: one copy per person on cross-posts (first list in To: delivers it), and the From now shows just the author's name (the address remains the list's — that part is required by SES and DMARC).