Internet Information Services

need fully-qualified hostname

If you see errors like the below

    Message delivery to the host 'xxx.xxx.xxx.xxx' failed while delivering to the remote domain 'terra.com.pe' for the following reason: An SMTP protocol error occurred.
    The SMTP verb which caused the error is 'HELO'. The response from the remote server is '504 <xxxxx>: Helo command rejected: need fully-qualified hostname
        

Then setup your fully qualified domain name.

Administrative Tools > IIS Manager -> HOST -> Default SMTP -> right click Properties -> Delivery -> Advanced -> full-qualified domain name