SyncApps will only sync specific records that do not contain these Group/Role email addresses. Reason for this is that these are not "person" emails because they might cause spam complaints and blacklisting.
To read a deep dive why Constant Contact and others do not send to these addresses read here.
These are the following Group/Role email addresses that SyncApps will ignore when Filtering feature is enabled:
If you are syncing any @yopmail emails with your email marketing this will cause errors to appear as Mailchimp and others have banned this domain so to avoid any errors just set up a filter in SyncApps with "Email does not contain @yopmail.com" criteria in your Sync Profile.