I'm not sure what you are talking about so I don't think it's a problem as my emails look normal in gmail and it doesn't show anything weird.
You might want to go over some of your email/message/security headers and look for anything unexpected (e.g. actual email address, device names, locations, etc.). The web-interface won't display most of what you'll find in there, with good reason.
Finding a way to access those headers from gmail will be a challenge though. Don't think I've ever found that button in the same place twice!
I don't think that this will enable you to send emails that conform to the DMARC standard (using DKIM and SPF). Might be ok for a side project, but in my opinion not enough for a small business.