The above response from our SMTP servers indicates that the credentials you have sent to our servers do not match the settings we have associated with your account
Please be aware that after a certain amount of incorrect authentication attempts, our system will block the IP address being used for a few minutes for your protection.
Your SMTP Credentials can be found online in the SocketLabs On-Demand Control Panel. Select your server, then go to Configuration > SMTP Credentials > View SMTP Credentials.
When passing SMTP Authentication information to our system, please keep in mind that we currently only support CRAM-MD5 or AUTH authentication types. Other authentication types will not be accepted.