Mailing Lists

Combination of #1 #2 #3 also contains the fixes of #1


Is the only reason this doesn't step on the toes of the action call above the fact that they both modify different state variables and both set `mailingLists` to null? They both call `combineRegister` when they're done, wouldn't all of that warrant to use an async flow to wait for the completion of both requests, for their common part at least? (Regeneration of mailing lists)