From: Chris on
I am running postfix as a SMTP front-end to my Exchange 2007 system.

When Exchange goes down, email is bounced back to the sender as undeliverable.

How can I setup postfix to 'spool' email until the backend SMTP server is online?

I have enclosed my main.cf, master.cf, and transport configs (at least the non-default ones). 

Main.cf:
default_process_limit = 600
minimal_backoff_time = 60
maximal_backoff_time = 240
queue_minfree = 80000000
smtp_helo_timeout = 20s
smtp_quit_timeout = 30s
smtp_mail_timeout = 20s
smtp_rcpt_timeout = 20s
smtpd_helo_required = yes
biff=no
disable_vrfy_command = yes
smtpd_recipient_restrictions =
     reject_invalid_hostname,
     reject_non_fqdn_sender,
     reject_non_fqdn_recipient,
     reject_unknown_sender_domain,
#     reject_unknown_recipient_domain,
     permit_mynetworks,
     reject_unauth_destination,
            reject_unauth_pipelining,
            check_recipient_access pcre:/usr/local/etc/postfix/recipient_checks.pcre,
     check_sender_access hash:/usr/local/etc/postfix/sender_checks,
     check_client_access hash:/usr/local/etc/postfix/client_checks,
     check_policy_service inet:127.0.0.1:12525,
#     check_policy_service inet:127.0.0.1:10023,
     permit
smtpd_data_restrictions =
     reject_unauth_pipelining,
     permit
smtpd_error_sleep_time = 5
smtpd_soft_error_limit = 5
smtpd_hard_error_limit = 10
smtpd_junk_command_limit = 10
smtpd_recipient_overshoot_limit = 100

maximal_queue_lifetime = 10d

#############
# Spam Transport
#############
transport_maps = hash:/usr/local/etc/postfix/transport
#relay_recipient_maps = hash:/usr/local/etc/postfix/exchange_recipients

Master.cf:
smtp      inet  n       -       n       -       -       smtpd
 -o smtpd_proxy_filter=127.0.0.1:10024
        -o smtpd_proxy_timeout=200
127.0.0.1:24 unix -      -       -     -       2  smtp
    -o smtp_data_done_timeout=1200
    -o disable_dns_lookups=yes
127.0.0.1:10025 inet n  -       -     -       -  smtpd
    -o content_filter=
    -o local_recipient_maps=
    -o relay_recipient_maps=
    -o smtpd_restriction_classes=
    -o smtpd_client_restrictions=
    -o smtpd_helo_restrictions=permit_mynetworks
    -o smtpd_sender_restrictions=
    -o smtpd_recipient_restrictions=permit_mynetworks,reject
    -o mynetworks=127.0.0.0/8
    -o maximal_queue_lifetime=10d
    -o strict_rfc821_envelopes=yes

transport:
##############
# Exchange Config
##############
#company.com            smtp:[mail.company.local]
acme.net       smtp:[10.10.10.50]
From: Ralf Hildebrandt on
* Chris <kingpinofdisks(a)yahoo.com>:
> I am running postfix as a SMTP front-end to my Exchange 2007 system.
>
> When Exchange goes down, email is bounced back to the sender as undeliverable.

Why? Show some logs for such a case

> How can I setup postfix to 'spool' email until the backend SMTP server is online?

That's the default :)

> I have enclosed my main.cf, master.cf, and transport configs (at least the non-default ones). 

postconf -n is very much preferred.
The config looks OK so far

--
Ralf Hildebrandt
Geschäftsbereich IT | Abteilung Netzwerk
Charité - Universitätsmedizin Berlin
Campus Benjamin Franklin
Hindenburgdamm 30 | D-12203 Berlin
Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
ralf.hildebrandt(a)charite.de | http://www.charite.de