Use for Bulk Mailings: optional, always or never for preferred emails?

Currently "Use for Bulk Mailings" checkbox is missing for preferred Email - non-primary locations.

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refering to this topic:
http://forum.civicrm.org/index.php?topic=3903.new;topicseen#new
it look not clear into contacts editing if preferred email is always or never used for Bulk Mailings, because is missing for this email the optional checkbox: "Use for Bulk Mailings".
the check box "Use for Bulk Mailings " is usef for all emails, apart preferred email and easily people don't understand if ts will be used or not in Bluk MAilings