This is where I came from. I got sick and tired of fighting with Hotmail and Gmail over 550 error mostly stating that no longer going to send email to any account permanently. Now with the error codes present you need to clean up your email problem and contact the email provider and go there hoops and loops to resolve your 550 error code. Sorry to say after two times around I lost my first IP address to Hotmail permanently this stopped me from sending email completely for a time.
Now when I got fired up with @stoo2000 Mail Bouncer I was set up still on SparkPost which was easy to setup and worked instantly. The first pass I wiped out a ton load of email accounts. Now after the 4.3.x update we got forced to move to SendGrdi which was more of a PITA to handle and setup IMHO. Now once its set up I'm still sending newsletters out monthly to capture that rogue email addresses that are floating on the website.
No longer have to filter out user into groups to ditch the older accounts and prevent sending email to the dead account.
Still, in all your 550 codes have to be fixed first. Then you can get to use the Mail Bouncer. Again I doubt Mail Bouncer will work with a standard email server because of the lack of API connection.