search-based mailings may or may not be re-used

there are a few bugs and issues that arise from search-based civimail mailings. here are steps to reproduce, and the effects.

1. run a search and select contacts
2. schedule/send a mass mailing from the action list
3. complete the first step – name the mailing and select an unsubscribe group

at this point, if you continue to the end of the wizard, the following will happen:

• two records will exist for the mailing in civicrm_mailing_group – one for the hidden smart group created to represent the search results, and one for the base group (unsubscribe)
• if you complete the mailing, it may not be re-used, because it is considered a search-based mailing

if you instead save the mailing, and then continue it, several things will change:

• you will be directed to the first step of the wizard, and the hidden smart group originally created will be listed in the include group list. but the unsubscribe group option will not be available, and the corresponding record in civicrm_mailing_group will have been removed.
• after completing the mailing, it will be available for re-use

we noticed the issue because we saw some search-based mailings were available for re-use and others were not. the issue is that the determination of whether a given mailing is search-based is dependent on the presence of that base/unsubscribe group record in the mailing_group table. when you save and continue, it does not exist, thus it is not treated like a search-based mailing.

so the main issue is to resolve the discrepancy. when continuing a search based mailing, you should be required to select and unsubscribe group.

however, I think this presents an opportunity to rethink the "re-use" restriction. that restriction was put in place because there's some ambiguity about how to handle a search based mailing when it is reused. should we use the static list of original recipients? should we rerun the search? if so, how does one view the search criteria originally used (and potentially modify it)?

those are valid concerns and potential areas of confusion. what if we allowed a re-use, but if the original mailing was search based, remove the recipients altogether and force the user to select from the group list? in other words – reuse means the content and configuration is copied, but the recipients need to be recreated. for a non-search based mailing, we would keep the behavior as currently (the recipient selections are preserved and copied).