Introduction
Think of it as a do-not-email list. To edit the Suppression list, go to the menu and select Subscribers -> Suppression list. An entry in the list excludes specific recipients from mailings, even if they are active in specific lists.
Possible values
E-mail address
e.g. john.doe@samplecompany.com
This entry means that no mailings will be sent to john.doe@samplecompany.com.
Domain
e.g. samplecompany.com
This entry means that no mailings are sent to recipients whose e-mail address ends in or contains samplecompany.com
Comparison with public Suppression lists
There is no automatic synchronization with a public Suppression / Robinson list. Legally speaking, this is not necessary, as those lists are only maintained on a voluntary basis.