Gmail

The dot (.) in a Gmail address has to be included if yours has one. To Groups.io, joe.smith and joesmith are two different people.

I Am On Gmail And I Don't Like Getting Copies Of My Messages

Go to Help Center > Members Manual > Understanding Groups.io accounts > Setting account preferences and viewing account information and scroll down to Receiving copies of your own messages that you email to groups. In step 4 of those instructions, clear (unselect) the I always want copies of my own emails checkbox. Then click the Update Preferences button.

I Get a Spoofing Warning On My Emails

See Help Center > FAQ > Why do I get a spoofing warning on my email messages?