Mail delivery failed: returning message to sender & gmail clients not receiving emails

I'm receiving this message when I use webmail. This is happening to the following addresses: jaz@imagebuild.com, megan@imagebuild.com, andi@imagebuild.com. My clients that use gmail are also having issues not receiving my emails. This is one of those addresses: traciebluseward@gmail.com.

For the webmail issue, because we thought it was something on their end, the client (Image Builders) contacted their IT support and this was his response:

1. The above is showing that your email that was NOT SENT AS REPLY showed delivered @ 1:50 PM.
2. The email you sent AS A REPLY @ Wed, 08 May 2024 14:45:12 -0400  never reached our server

Adrian also found that your domain, dingo-blue.com, was found on a blacklist for 2 Spamblocker websites. See below:

The gmail issue has been ongoing. The webmail issue started this week. Your assistance would be appreciated!