Use the following commands in the Exchange Shell to Whitelist either a whole domain or a single email address

To check whats currently whitelisted:

Get-ContentFilterConfig

To whitelist one email address:

$list = (Get-ContentFilterConfig).BypassedSenders

$list.add(“new.mail@address.com”)

Set-ContentFilterConfig -BypassedSenders $list

To whitelist an entire domain:

$list = (Get-ContentFilterConfig).BypassedSenderDomains

$list.add(“domain.com”)

Set-ContentFilterConfig -BypassedSenderDomains $list