#GMail is harmful to e-mail ecosystem; its antispam blocking policy matches too many valid messages as spam.
It blocked LastPass email leak warning email, because it contained "a link" to a leaked site.
It blocked an e-mail from goverment agency addressed directly to me.
It discriminates all non-gmail servers, and it's pretty much impossible to own a private SMTP server these days, because GMail will classify everything as spam.
It's not how e-mail should work.
Consider dropping GMail.