Say I sent a bunch of emails last year to people that weren't on any list then. I now want to be able to email the same people again, all in one shot ideally. I think I can do a reasonable job of creating a search query that will return the emails that I had sent. I'm thinking of trying to add some sort of label to the emails themselves, or to the email addresses (they are not currently in contacts), and then sending an email with the same text to all of them.
This is for mailing some ski places for availability in case anyone is wondering.