If I import contacts via a CSV file and indicate a home email, the email address does get imported without any issue.
However, in order to send an email to the contact (in my case sending to an entire group in CiviMail), I currently need to open the contact and select "Add or edit email", and re-save it in order for it to be active.
Once it is active (which can be determined when the field label "Home Email" is then bolded), CiviMail then recognizes the email address and can then send.
Update: I should add, this could likely be a bug since the issue is also present on the Civi demo site at https://civicrm.demo.civihosting.com