I've been looking around further, and it seems like it might work to use SSL over port 465, but this is deprecated and not supported by iRedMail out-of-the-box (I think). Is there any workaround to get iRedMail to use SSL over port 465 for smtp?
The other option is to disable encryption altogether, but I can't seem to figure that out either. I tried commenting out all the tls-related lines in /etc/postfix/main.cf and reloading postfix. Then in Outlook I tried smtp port 25 with No encryption, but it's still not working. But I've found that even with this configuration, I can't connect via POP3 without using SSL in Outlook, so I don't think I'm disabling the encryption stuff in postfix correctly.
Here's my main.cf in an attempt to disable tls/ssl and use port 25 with no encryption.
# See /usr/share/postfix/main.cf.dist for a commented, more complete version
# Debian specific: Specifying a file name will cause the first
# line of that file to be used as the name. The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
# appending .domain is the MUA's job.
append_dot_mydomain = no
# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
readme_directory = no
# TLS parameters
#smtpd_tls_cert_file = /etc/ssl/certs/iRedMail_CA.pem
#smtpd_tls_key_file = /etc/ssl/private/iRedMail.key
#smtpd_use_tls=no
#smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
#smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.
myhostname = mx.backsaba.com
alias_maps = hash:/etc/postfix/aliases
alias_database = hash:/etc/postfix/aliases
myorigin = mx.backsaba.com
mydestination = $myhostname, localhost, localhost.localdomain, localhost.$myhostname
relayhost =
mynetworks = 127.0.0.0/8
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = ipv4
virtual_alias_domains =
mydomain = backsaba.com
mynetworks_style = subnet
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_reject_unlisted_recipient = yes
smtpd_reject_unlisted_sender = yes
smtpd_sender_restrictions = permit_mynetworks, reject_sender_login_mismatch, permit_sasl_authenticated
delay_warning_time = 0h
maximal_queue_lifetime = 1d
bounce_queue_lifetime = 1d
proxy_read_maps = $canonical_maps $lmtp_generic_maps $local_recipient_maps $mydestination $mynetworks $recipient_bcc_maps $recipient_canonical_maps $relay_domains $relay_recipient_maps $relocated_maps $sender_bcc_maps $sender_canonical_maps $smtp_generic_maps $smtpd_sender_login_maps $transport_maps $virtual_alias_domains $virtual_alias_maps $virtual_mailbox_domains $virtual_mailbox_maps $smtpd_sender_restrictions
smtp_data_init_timeout = 240s
smtp_data_xfer_timeout = 600s
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks,permit_sasl_authenticated, check_helo_access pcre:/etc/postfix/helo_access.pcre
queue_run_delay = 300s
minimal_backoff_time = 300s
maximal_backoff_time = 4000s
enable_original_recipient = no
disable_vrfy_command = yes
home_mailbox = Maildir/
allow_min_user = no
message_size_limit = 15728640
virtual_minimum_uid = 1002
virtual_uid_maps = static:1002
virtual_gid_maps = static:1002
virtual_mailbox_base = /var/vmail
transport_maps = proxy:mysql:/etc/postfix/mysql/transport_maps_user.cf, proxy:mysql:/etc/postfix/mysql/transport_maps_domain.cf
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql/virtual_mailbox_domains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql/virtual_mailbox_maps.cf
virtual_alias_maps = proxy:mysql:/etc/postfix/mysql/virtual_alias_maps.cf, proxy:mysql:/etc/postfix/mysql/domain_alias_maps.cf, proxy:mysql:/etc/postfix/mysql/catchall_maps.cf, proxy:mysql:/etc/postfix/mysql/domain_alias_catchall_maps.cf
sender_bcc_maps = proxy:mysql:/etc/postfix/mysql/sender_bcc_maps_user.cf, proxy:mysql:/etc/postfix/mysql/sender_bcc_maps_domain.cf
recipient_bcc_maps = proxy:mysql:/etc/postfix/mysql/recipient_bcc_maps_user.cf, proxy:mysql:/etc/postfix/mysql/recipient_bcc_maps_domain.cf
relay_domains = $mydestination, proxy:mysql:/etc/postfix/mysql/relay_domains.cf
smtpd_sender_login_maps = proxy:mysql:/etc/postfix/mysql/sender_login_maps.cf
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain =
broken_sasl_auth_clients = yes
smtpd_sasl_security_options = noanonymous
smtpd_sasl_authenticated_header = no
smtpd_recipient_restrictions = reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_non_fqdn_sender, reject_non_fqdn_recipient, reject_unlisted_recipient, check_policy_service inet:127.0.0.1:7777, check_policy_service inet:127.0.0.1:10031, permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, reject_non_fqdn_helo_hostname, reject_invalid_helo_hostname
smtpd_end_of_data_restrictions = check_policy_service inet:127.0.0.1:10031
#smtpd_tls_security_level = may
#smtpd_tls_loglevel = 0
#smtpd_tls_CAfile = /etc/ssl/certs/iRedMail_CA.pem
####smtpd_tls_auth_only = no
#tls_random_source = dev:/dev/urandom
mailbox_command = /usr/lib/dovecot/deliver
virtual_transport = dovecot
dovecot_destination_recipient_limit = 1
smtpd_sasl_type = dovecot
smtpd_sasl_path = ./dovecot-auth
#content_filter = smtp-amavis:[127.0.0.1]:10024
smtp-amavis_destination_recipient_limit = 1
