

Mail extensions with plus are free. With your own domain you can set up a catchall alias ad well if you want to accept mail for any mail address https://kb.mailbox.org/en/private/e-mail-article/how-to-use-mail-extensions/
https://kb.mailbox.org/en/private/e-mail-article/using-catch-all-alias-with-own-domain/
Do you replace the power banks to keep them charged to 70%? Maybe also add some ham radios and walkie talkies to the stash.