When you need to White list Sender/Domain to Exchange 2010, you have to use power shell as this is not available from GUI

To view what currently is in the White List for senders, fire open the Exchange Management Power shell:
1- for white list individual e-mail address:
(Get-ContentFilterConfig).ByPassedSenders

2- for white listed domains
(Get-ContentFilterConfig).ByPassedSenderDomains

Now how to add an individual e-mail address or domain:
1- To whitelist a domain e.g. johnyassa.com you’d do the this:

$WhiteDomain = (Get-ContentFilterConfig).BypassedSenderDomains

$WhiteDomain.add(“johnyassa.com”)

Set-ContentFilterConfig -BypassedSenderDomains $WhiteDomain

2- To White list a sender e.g. john@johnyassa.com you’d do this:

$WhiteSender = (Get-ContentFilterConfig).BypassedSenders

$WhiteSender.add(“john@johnyassa.com”)

Set-ContentFilterConfig -BypassedSenders $WhiteSender

Now you can re run the first 2 commands and check their results to confirm your adding success