Exchange 2010 Send mail

Question

We have Exchange setup but are running into an issue where anyone can spoof an email account from our domain and it goes out using SMTP through command prompt. I want to know if it is possible to set up Exchange so whenever anyone tries to send an email
out from our domain it verifies the account exists and also looks for a password. This will prevent people from being able to send email pretending they are someone else. Here are accouple examples
1) I can use [email protected] and send an email to [email protected] and it goes through with no password required using smtp through command prompt both accounts exist but the sender is not really josh.smith.
2) I can send an email from [email protected] to [email protected] but [email protected] does not exist on the domain.
Thanks
Kevin

Answer 1

There are two ways to do this - 1) you can configure your receive connectors to only allow messages from specific IP addresses, or 2) you can configure the ms-exch-smtp-accept-authoritative-domain-sender permission on the domain (use Get-ReceiveConnector
“Internet ReceiveConnector” | Get-ADPermission -user “NT AUTHORITY\Anonymous Logon” | where {$_.ExtendedRights -like “ms-exch-smtp-accept-authoritative-domain-sender”} | Remove-ADPermission
to do this).  The first allows messages inbound from the Internet, which may be useful when people use their internal address for signing up on external websites.  The second blocks everything using your domain that's not authenticated.