Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
The 'Action failed Status 5.2.0'
is the important part of that error message (-and thank you for quoting it, that is quite essential to an accurate diagnosis.)
The '5' part means it's a 'hard error', not at all uncertainly.
And being '5.2' signifies a 'mailbox status uncertain' error, or the like. In short, it may not be the SMTP setup, but rather the status of the address you sent your test email to. (I admit this is slightly questionable... but if I'm wrong at my initial estimation of the situation, let me know, and we'll work out the real solution with a little back-and-forth communication.)
In short, if that error was the result of sending an email as a test, you may have to try sending to another email address to be quite sure it's the SMTP server rather than the recipient email address/inbox status.
What did you get the error message from?
My impression was that it was from a test email that you tried to send, using sendmail.
In which case my suggestion amounts to sending a test email to a different destination.