CiviMail send mails only to certain location type
I have the following Usecase: A big organization is using CiviCRM for mailing marketing of different departments. Their Contacts can have several email addresses (with different location types). A Contact has an email address that is used by department A for the communication with the customer via mass mailing. But department B wants to communicate with the customer via another email address via mass mailing.
Currently there seems to be no possibility to select which email address location type should be preferred for an specific mass mailing (of department A - while department B creates another mass mailing and wants to select their preferred location type for another mass mailing).
Possibilities in CiviCRM: I can create different location types for the different purposes. I can add email addresses with the corresponding location type. I can select one email address as the primary email address. I can select one email address for mass mailing. Problem: But I can not select different email addresses for different mass mailings
Possible Workaround: I could keep the two contacts as duplicates in the system. But the customer still still want to have an overall overview over their communication with this contact - so simply having duplicates is not an attractive option.
Feature Request: What I would need is the feature of selecting the preferred location type to be used for a specific mailing. If the contact has no email address of this communication type the fallback option could be the primary / bulk-e-mail-address
What effort would it take to create such a feature? I guess it would make most sense to implement it into the civicrm core - do you aggree?