Configurng outbound smtp, sent message return error: "SMTP Error: Data not accepted"

So having an issue configuring outbound smtp to work again after an upgrade to phab version: d9b41d3a0f878d91b7485007d53998516d30731d

I’ve loaded my smtp config via:
sudo bin/config set cluster.mailers --stdin < conf/local/smtp.json

With my config being:

[
  {
    "key": "sparkpost-mail",
    "type": "smtp",
    "options": {
      "host": "smtp.sparkpostmail.com",
      "port": 587,
      "user": "USER_Name",
      "password": "PASSWORD",
      "message-id": false
    }
  }
]

After loading that in and making an update to a ticket or trying to send a test message I keep getting an error like the below:

 PROPERTIES 
ID: 166503
Status: queued
Related PHID: 
Message: SMTP Error: Data not accepted.

 PARAMETERS 
sensitive: 1
mustEncrypt: 
cc: []
subject: test
is-bulk: 
mailtags: []
to: ["PHID-USER-cisc3qmiby2wt4lussk3"]
message.type: email

 HEADERS 

 TEXT BODY 
sdfsdf


 HTML BODY 
(This message has no HTML body.)

Any help that could be provided would be helpful, since I’m at a bit of a loss. Already checked with the python smtplib that I can auth with my credentials to that provider.