Complete procedures with a way back.

Inventory storage and identity backends, create application-consistent copies, protect indexes and Sieve data, encrypt offsite, restore one user, and verify IMAP state.

Install Dovecot, set mailbox location, require TLS, protect certificates, choose authentication mechanisms, constrain listeners, and test IMAPS and STARTTLS.

Create a single storage identity, define virtual passdb/userdb, map domains safely, build Maildir permissions, enable quotas, and test enforcement and reporting.

Combine SMTP, submission, virtual domains, Dovecot authentication, LMTP delivery, IMAP TLS, quotas, Rspamd, DKIM, DNS, backups, and end-to-end validation.

Add a dedicated submission service, require STARTTLS and SASL, integrate Dovecot authentication, constrain relaying and abuse, and test safe failure modes.