Questions[postfix](server)

I have a backup mail server in case of a failure on the main one. In that case of failure, mails come on the backup server and stay there until the main one is back.

If I wait some times, the delivery will be done automatically as soon as the main server is back but it can be long. So how to force a send retry of all the mails?

For exemple : postqueue -p : give me a list of mails

I then tried postqueue -f (from man page : Flush the queue: attempt to deliver all queued mail.). It surely flushed the queue but mails were not been delivered...

I have Postfix setup on my server so that I can send outgoing mail using the command-line:

mail -s "Subject" [email protected]

1. Is this using Sendmail or Postfix ?
2. Is "Sendmail" just a software category or a distinct program ?
3. If something is "Sendmail-ready" does that mean it will work with Postfix ?

Everything I've read online seems to use these two terms interchangeably.

I have just finished setting up a Postfix mail server on a linux (ubuntu) platform. I have it sending and receiving email and it is not an open relay. It also supports secure smtp and imap.

Now this is a pretty beginner question but should I be leaving port 25 open? (since secure smtp is preferred). if so then why?

Also what about port 587?

Also should I require any authentication on either of these ports?

Please excuse my ignorance in this area :P

My system configuration script does an "apt-get install -y postfix". Unfortunately the script is halted when the postfix installer displays a configuration screen. Is there a method to force postfix to use the defaults during installation so that an automated script can continue to the end?

Does the postfix installer maybe check for existing configuration in /etc/postfix, and if it exists, not bother the user with the configuration screen?

This morning, in order to correct a problem with a name mismatch in the security certificate, I followed the recommended steps from How to fix mail server SSL?, but now, when attempting to send an email from a client (in this case the client is Windows Mail), I receive the following error.

The rejected e-mail address was '[email protected]'. Subject 'This is a test. ', Account: 'mail.domain.com', Server: 'mail.domain.com', Protocol: SMTP, Server Response: '554 5.7.1 : Relay access denied', Port: 25, Secure(SSL): No, Server Error: 554, Error Number: 0x800CCC79

Edit: I can still retrieve emails from this account, and I send emails to other accounts at the same domain. I just can't send emails to recipients outside of our domain.

I tried disabling TLS altogether but no dice, I still get the same error.

When I check file mail.log, I see the following.

Jul 18 08:24:41 company imapd: LOGIN, [email protected], ip=[::ffff:111.111.11.11], protocol=IMAP
Jul 18 08:24:42 company imapd: DISCONNECTED, [email protected], ip=[::ffff:111.111.11.11], headers=0, body=0, rcvd=83, sent=409, time=1
Jul 18 08:25:19 company postfix/smtpd[29282]: connect from company.university.edu[111.111.11.11]
Jul 18 08:25:19 company postfix/smtpd[29282]: NOQUEUE: reject: RCPT from company.university.edu[111.111.11.11]: 554 5.7.1 <[email protected]>: Relay access denied; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<UserPC>
Jul 18 08:25:19 company postfix/smtpd[29282]: disconnect from company.university.edu[111.111.11.11]
Jul 18 08:25:22 company imapd: DISCONNECTED, [email protected], ip=[::ffff:111.111.11.11], headers=13, body=142579, rcvd=3289, sent=215892, time=79

File main.cf looks like this:

#
# Postfix MTA Manager Main Configuration File;
#
# Please do NOT edit this file manually;
#

#
# Postfix directory settings; These are critical for normal Postfix MTA functionallity;
#

command_directory = /usr/sbin
daemon_directory = /usr/lib/postfix
program_directory = /usr/lib/postfix

#
# Some common configuration parameters;
#

inet_interfaces = all
mynetworks = 127.0.0.0/8
mynetworks_style = host

myhostname = mail.domain.com
mydomain = domain.com
myorigin = $mydomain

smtpd_banner = $myhostname ESMTP 2.4.7.1 (Debian/GNU)
setgid_group = postdrop

#
# Receiving messages parameters;
#

mydestination = localhost, company 
append_dot_mydomain = no
append_at_myorigin = yes
transport_maps = mysql:/etc/postfix/transport.cf

#
# Delivering local messages parameters;
#

mail_spool_directory = /var/spool/mail
mailbox_size_limit = 0
mailbox_command = procmail -a "$EXTENSION"

biff = no

alias_database = hash:/etc/aliases

local_recipient_maps =

#
# Delivering virtual messages parameters;
#
virtual_mailbox_maps=mysql:/etc/postfix/mysql_virt.cf
virtual_uid_maps=mysql:/etc/postfix/uids.cf
virtual_gid_maps=mysql:/etc/postfix/gids.cf
virtual_mailbox_base=/usr/local/virtual
virtual_maps=mysql:/etc/postfix/virtual.cf
virtual_mailbox_domains=mysql:/etc/postfix/virtual_domains.cf


#
# SASL paramters;
#
smtp_use_tls = yes
smtpd_use_tls = yes
smtpd_tls_auth_only = yes
smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_session_cache_timeout = 3600s

smtp_tls_CAfile = /etc/postfix/ssl/smptd.pem
smtp_tls_cert_file = /etc/postfix/ssl/smptd.crt
smtp_tls_key_file = /etc/postfix/ssl/smptd.key

smtpd_tls_CAfile = /etc/postfix/ssl/smptd.pem
smtpd_tls_cert_file = /etc/postfix/ssl/smptd.crt
smtpd_tls_key_file = /etc/postfix/ssl/smptd.key

smtpd_sasl_auth_enable = yes

smtpd_sasl_security_options = noanonymous

smtpd_sasl_local_domain =

broken_sasl_auth_clients = yes

smtpd_sender_restrictions =
        permit_sasl_authenticated
        permit_mynetworks

smtpd_recipient_restrictions =
        permit_sasl_authenticated
        check_recipient_access hash:/etc/postfix/filtered_domains
        permit_mynetworks
        reject_unauth_destination

As a side note, my employer wants to be able to send emails from clients (Thunderbird and Outlook) both from within our local network and outside it.