gmail transmission

I too am experiencing a gmail reject, and, send back action. my issue is as follows: What I was able to determine is that the reason my gmail will not transmit, and is consistently being returned is due to the fact that; "The sender (myself) is not authenticated, whereby Gmail requires all senders to authenticate with either SPF or DKIM.

However, my attempted gmail transmissions are being returned due to the facts of the-Authentication Results: of which I did not pass either (DKIM or SPF). Can anyone guide myself on how to authenticate accordingly, and thereafter have the ability to transmit to gmail addresses from my-homestead/roundcube email. Standing by...

Thank you,

Victoriano