Update instructions: No special steps required other than updating the binary.

Important bug fixes:

• When dkim-signing submitted messages, use the domain from the "message from header" instead of "smtp mail from". If you had an account with multiple addresses in different domains, then with some mail clients the DKIM signature on outgoing messages could be for the wrong domain.

Changes:

• Add "mox localserve", a subcommand for running mox locally for email-related testing/developing. Localserve creates a config for listening on localhost for imap/smtp/submission/http, on port numbers 1000 + the common service port numbers. All incoming email is accepted (if checks pass), and a few pattern in localparts are recognized and result in delivery errors.
• Implement configurable (rate) limits on outgoing messages, per account. By default an account can send 1000 messages per day, to max 200 first-time receivers. The goal is to limit damage spammers can do with compromised accounts.
• In domains.conf, for an account, the Destinations mapping will now always use full email addresses, no longer localparts relative to the Domain configured for the account. The old form with just a localpart is still accepted. When writing domains.conf through the cli commands or admin web pages, the destinations will automatically be written with full email addresses. In the future, support for the localpart-only form will be removed.
• Implement a catchall address for a domain, an address without localpart (i.e. starting with "@"). If an incoming message does not match a configured address, it is delivered to the account configured that has the catchall address configured.
• ACME TLS certificate validation can also be done with method http-01 (previously only with tls-alpn-01).
• If you run mox behind a NAT, you can now specify "IPsNATed: true" in the SMTP listener to skip a few DNS checks that previously would always fail due to the IPs being NATed.
• Add subcommand "mox dkim sign", useful for testing signatures.
• For a "WebRedirect" rule, don't match a request if the destination URL would result in the same URL, causing a redirect. By not matching, the next configuration rules are evaluated for a match.
• Various smaller technical and user-experience improvements.

Thanks to everyone who sent in feedback (e.g. by creating an issue on github). It's much appreciated and essential for improving mox!