If you know your domain is not being blacklisted, then you may want to check that your SPF is configured correctly, or whatever domain email signing scheme you use. Also, does /var/log/mail.log show a difference between email being sent by roundcube versus any other email client?

Hey thanks for replying back,

I followed the link you provided and followed the steps. It did not return an error however it did not go through as i tested it with my personal email. I used the google mx records that the tutorial suggested. The error logs show that the emails are trying to send from my domain ip. Nethier does roundcube or my other email client allow me to send email from it, only receive it. I would want to be able to send email from my domain as well as receive it. Any other thoughts?

@Artmanstan - So using SPF removed the message "...its being blocked by the email server", but the emails are still not being delivered?

What was the last reported status in /var/log/mail.log when you sent from your domain to another domain? (Look for the string "status=" in the mail log). Need to narrow down the point where the email hand-off occurred and what happened.

Yea it stopped the error message but doesn't deliver the message. I think it's cause using the Google mx credentials. How could I find or generate my own mx credentials so I can send emails from my own domain's?

@Artmanstan - Use a free (for basic diagnostics) site like mxtools.com. For the mxtoolbox site, use the button with the pulldown menu to do the test you like (like examining your MX records, blacklisting checks, testing your email server and your reverse DNS configuration, etc). Good luck.