To create a Sublist follow these steps:
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From the contacts tab click the contact list you would like to create a Sublist segmented list from.
Select the contacts to create the Sublist and click 'Add Tags'.
Add the tag you would like to tag the selected contacts. Use a tag you haven't used before so you don't get confused. Click 'Save'.
Click the 'Tags' button and all your saved tags will appear.
Select the tag you saved your contacts as for your Sublist. Click 'Search'.
The tagged contacts should appear. Click the 'Save as Sublist' buttonClick on Add Segment under the “+Add” option.
Add a name for your segment and then Save.
Filters opion will allow you to set up conditions under which contacts will be filtered here, for example a certain Contact status or Email activity.
Once you Save, shortly after, contacts will appear in the Sublist.
Your new Sublist will appear under the main contact list you created your Sublist from.