If MailChimp doesn’t accept a contact during a sync you’ll find an error message in the EmailMarketing log and the contact will end up in the “Errors” subgroup in Daylite.
In most cases MailChimp doesn’t accept a contact due to one of the following reasons:
an email address bounced (i.e. receiving mail server rejected the mail) during a previous mailing and has therefore been removed from the subscribers list on mailchimp.com. In order to re-add such a contact, you will need to delete this contact from the “cleaned” list on mailchimp.com first (select MailChimp list -> “Subscribed drop-down menu -> Cleaned).
a contact has no email address
a contact’s email address is not set as the primary address in Daylite
a contact’s email address contains leading or trailing whitespace
generic “role” addresses such as “info@, sales@, webmaster@, etc” are not accepted by MailChimp.