I have similar issues. I am using gmail. Gmail has recently instituted
a vigorous protocol, refusing to accept emails from servers which
don't have a MX record etc. I see some original emails due to
responses to this email.

Karl.

On Tue, Jul 23, 2024 at 5:22 PM Mark McCulley <mark@markmcculley.com> wrote:
>
> I just noticed that if I press Reply or Reply All to respond to a list email, the list address goes into the CC field and the list ignores my email. I must manually put the list address into the TO field to get my email processed and distributed to the list.
>
> I am using Apple’s email client on iOS and MacOS.