With cdos email and submit them to the following error:

Email cannot be sent to the SMTP server, transmission error code of 0 x800ccc67, server response for 421 4.3.2 Service not available, closing transmission channel

As need to open relay mail server, open all IP, doing so will be entirely problem (spam and virus messages flood), how to solve?
IP (joined the specified client, the client on this can send success.)
It is strange that I'm using the mail server to specify a user name + password sent, why not? (and relay open all client IP)?


Smtpauthenticate=1
Sendusername="XXX"
Sendpassword="XXXXX"