Like many other service providers, SocketLabs On-Demand services require a username and password to access your account. The above response from our SMTP servers indicates that you have not attempted to authenticate or send any login credentials to our servers, and thus you will be unable to inject messages via SMTP until you have provided the correct credentials. Please be aware that after a certain amount of incorrect authentication attempts, our system will blacklist 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. If you are using our SocketLabs On-Demand Service as a SmartHost for relaying mail from your own server, please see the following article for more information on how to properly configure some common scenarios: How to increase SMTP performance when sending messages through Socketlabs
In some cases, we have found that the systems our customers use to interface with our service are incapable of passing login information along with an SMTP request. It is our strong recommendation that in those cases you contact the vendor of the software you are using for support in how to pass authentication credentials along with your SMTP requests.
If it is not possible to resolve this from the software perspective, we do have an option of whitelisting a static IP address so that all requests from that IP address will pass through into our system and through your account without requiring any credentials. This does open a potential security hole so we do not recommend this option, but if it is necessary and you have full control over the network traffic for that IP address (such as your own mail server that is being used for SmartHost relaying to us), please open a ticket in our Support Center requesting that we whitelist your IP address. This option is not available to Free Accounts.