What you describe having done is exactly correct. I am subscribed as "no email" but just changed to "all messages" prior to composing this response via the web. It may be that Groups.io uses an intelligent filter that doesn't e-mail your own messages composed via the web back to you.
I'll report back in a few minutes as to whether this one appears in my inbox as an email message. -- Brian
The real art of conversation is not only to say the right thing in the right place but to leave unsaid the wrong thing at the tempting moment.