To create mailing lists of your contacts grouped and segmented according to their information, roles and custom fields, go to Segments under Analytics.
Click to create a new segment, choose usertype, associated fields viz. First name, Last name, Email etc, Filter by custom fields if needed.
Select the date range from the top right.
Click on Save.
This segment shall now be displayed in the drop down when you want to send an email campaign. You can see an email campaign's report once the campaign is sent.