This is what Drush says when trying to enable the module:

/PATH_TO/sites/all [develop]$ drush en contact_entityform -y
contact_entityform was not found.                                                                                                                                         [warning]
The following projects provide some or all of the extensions not found:                                                                                                   [ok]
contact_entityform
Would you like to download them? (y/n): y
Project contact_entityform (7.x-1.0-alpha1) downloaded to /PATH_TO/sites/all/modules/contrib/contact_entityform.    [success]
The following projects have unmet dependencies:                                                                                                                           [ok]
contact_entityform requires entity2text, entity_rules, email
Would you like to download them? (y/n): y
Project entity2text (7.x-1.0-alpha2) downloaded to /PATH_TO/sites/all/modules/contrib/entity2text.                  [success]
Project entity_rules (7.x-1.0-alpha4) downloaded to /PATH_TO/sites/all/modules/contrib/entity_rules.                [success]
Project email (7.x-1.3) downloaded to /PATH_TO/sites/all/modules/contrib/email.                                     [success]
The following extensions will be enabled: contact_entityform, entity2text, entity_rules, entityform_notifications, entityform, email
Do you really want to continue? (y/n): y
Creating default object from empty value entity.module:876                                                                                                                [warning]
WD rules_config: PDOException: SQLSTATE[HY000]: General error: 1364 Field 'plugin' doesn't have a default value: INSERT INTO {rules_config} (name, status, module) VALUES [error]
(:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2); Array
(
    [:db_insert_placeholder_0] => rules_entitiyform_email_site_admin_
    [:db_insert_placeholder_1] => 2
    [:db_insert_placeholder_2] => contact_entityform
)
 in drupal_write_record() (line 7239 of /PATH_TO/includes/common.inc).
SQLSTATE[HY000]: General error: 1364 Field 'plugin' doesn't have a default value                                                                                          [error]