On my home Ubuntu box, postfix is configured to relay all outgoing email to outgoing.verizon.net. Unfortunately this includes local user-to-user email (e.g., from local cron jobs to me, or from me to myself) which should not need to travel off-machine. Is there a way to tweak my configuration (below) so local email is delivered without leaving my machine?
Note: I don't run a mail server (on port 25) but rather run fetchmail every five minutes to download from an IMAP server.
main.cf:
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = mycomputer.example.com
masquerade_domains = example.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = $myhostname, localhost.localdomain, localhost
relayhost = [outgoing.verizon.net]:587
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
smtp_sasl_auth_enable = yes
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options =
smtpd_sasl_auth_enable = no