relaying is forwarding/sending to email addresses that are not administered by the specific server you are conecting to...for example, if my server is the google's gmail, then emails to @SqlServerCentral.com would be relayed from gmail to SSC; emails @gmail.com are on that server, and just go thru standard spam filtering before being delivered.
the default settings of any mail server are designed to prevent the server from being able to relay "spam"
to avoid all those viagra and male enhancement pills and stuff like that, a mail server is set up typically only allows relaying in two situations.
1. If using anonymous authentication, only mail coming from IP addresses already placed in the white-list get to relay; this is typically where the IP address of the webserver(or in this case, a SQL Server) has been added to the list of permitted machines. That's where you get with the administrator of the mail server, to add your IP.
A lot of times the server allows any machine on the internal LAN to relay by default.
2. instead of anonymous authentication, you use basic authentication, and provide a username and password. Because you are an actual user, In that situation, the mail server usually allows relaying. some servers require both...an account and also the IP address to be on the "white-list" of allowed machines
try switching to use a valid account first, instead of anonymous authentication. if that fails, get with your mail admin.
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