/etc/apparmor.d/usr.lib.dovecot.deliver is in apparmor-profiles 2.7.102-0ubuntu3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | # Author: Dulmandakh Sukhbaatar <dulmandakh@gmail.com>
#include <tunables/global>
/usr/lib/dovecot/deliver flags=(complain) {
  #include <abstractions/base>
  #include <abstractions/nameservice>
  capability setgid,
  capability setuid,
  # http://www.postfix.org/SASL_README.html#server_dovecot
  /etc/dovecot/dovecot.conf r,
  /etc/dovecot/{auth,conf}.d/*.conf r,
  /etc/dovecot/dovecot-postfix.conf r,
  @{HOME} r,
  @{HOME}/Maildir/ rw,
  @{HOME}/Maildir/** klrw,
  @{HOME}/mail/ rw,
  @{HOME}/mail/* klrw,
  @{HOME}/mail/.imap/** klrw,
  /usr/lib/dovecot/deliver mr,
  /var/mail/* klrw,
  /var/spool/mail/* klrw,
  # Site-specific additions and overrides. See local/README for details.
  #include <local/usr.lib.dovecot.deliver>
}
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