To bypass all filtering for email recipients in a domain or set of domains in Messaging Gateway (SMG) the domain will need to be exempted from filtering at both the reputation and policy level
This will cause SMG to bypass all filtering for email addresses in that domain. Messages which contain recipeint addresses in multiple email domains will be split into multiple messages as usual and the filtering policies for the respective recipients will be applied as expected.
Please see the Messaging Gateway Adminstration Guide for further information on creating and configuring policy groups.
Note: This does not bypass IP based reputation such as Connection Classification and the Local Bad Sender IP list.