21704: ssnd-SMTP server returned an error msg

Partial domain not allowed:

Check the encoded "Email From", "Destination" and "CC" email addresses. Check for spaces in the address and remove them.

Bad address:

Check the encoded "Email From", "Destination" and "CC" email addresses. Check for spaces in the address and remove them.

Domain does not exist: 

Check the "EMail 'From' User name" parameter (the Sender Name) configured in the STMP configuration page.
Usually, you can put what you want in this field BUT some SMTP server checks if the Domain Name (the ewon.biz in support@ewon.biz) really exist.
Practically, the Domain must be valid but there is no need that the mailbox really exist (usually).

For instance, you can use eMail sender name like  ewon147@ewon.biz  even if there is no real mailbox for this "ewon147 user" defined in our Mail Server.

Relaying mail is not allowed: 

This message indicates that the SMTP server which you encoded in the eWON does not allow to relay emails coming from the Internet connection which the eWON is using. To solve this problem check which SMTP server must be used with the Internet connection of the eWON. 

If eWON uses its second Ethernet interface to connect on Internet, then check which DSL operator is used for the company network and then specify inside the eWON the SMTP server which has to be used for this DSL operator.

If eWON uses a modem connection for the Internet access, then you must specify in the eWON the SMTP server of the GSM operator. Best contact your SIM card provider to inform you about the SMTP server to use.

You can also check if you can find the needed information here: Countries Info and Specificities.

Gmail SMTP server:

The SMTP server used by GMail is not a standard SMTP server. eWON is not compatible with the SMTP server protocol used by Gmail.