

The point is not to self-host email (not entirely anyway; you’ll always need an SMTP relay with good IP reputation, e.g. mailgun), but you can use a regular web hosting company and buy your own domain there or separately via porkbun etc… Your bank won’t have a clue what email you use, you’re just paying a web hosting co. / domain registrar.
Dunno about Posteo or Mailbox but couldn’t really recommend a dedicated email provider as I alluded to earlier - cPanel gives me complete control, although it’s your own responsibility to set up mailboxes and configure it how you like. There’s a way to create a filter to give yourself a catch-all email (use a unique email address when signing up for things), and I turn off SpamAssassin as I prefer 100% deliverability and no false positives. If an email address ‘leaks’, I can simply blackhole it in cPanel.
Used to use Namecheap for domains but now Porkbun (much cheaper). Been using KeePass for a number of years too, but switching over to Bitwarden imminently. :)