Part 1 of this tutorial can be found here: https://forum.howtoforge.com/thread...heme-in-an-ispconfig-mailserver-part-1.89827/ Where the basic installation of Postsrsd and implementation in Postfix is covered. Part 2 covers the recovery of the broken functionality behind ISPConfig's ability to configure a relayhost per domain and entire host. For this we need to setup a second Postfix instance. I've called mine "postfix-relay" in group "mta" and will be running it on port 2525. Create the second instance: Code: postmulti -e init postmulti -I postfix-relay -G mta -e create Copy /etc/postfix/main.cf to /etc/postfix-relay/main.cf Delete lines in /etc/postfix-relay/main.cf: Code: dovecot_destination_recipient_limit = 1 smtpd_sasl_type = dovecot smtpd_restriction_classes = greylisting greylisting = check_policy_service inet:127.0.0.1:10023 smtpd_milters = inet:localhost:11332 non_smtpd_milters = $smtpd_milters milter_protocol = 6 milter_mail_macros = i {mail_addr} {client_addr} {client_name} {auth_authen} milter_default_action = accept multi_instance_wrapper = ${command_directory}/postmulti -p -- multi_instance_enable = yes multi_instance_directories = /etc/postfix-relay multi_instance_group = mta Change lines in /etc/postfix-relay/main.cf: Code: inet_interfaces = all inet_protocols = all to Code: inet_interfaces = loopback-only inet_protocols = ipv4 Change in /etc/postfix-relay/master.cf Code: smtpd inet n - y - - smtpd to Code: 127.0.0.1:2525 inet n - y - - smtpd Enable and start the second instance of Postfix: Code: postmulti -i postfix-relay -e enable postmulti -i postfix-relay -p start I had issues with resolving domains in Postfix because not all chroot related folders where created. This was solved with a reboot of the server. Now that the second instance of Postfix is up and running we need to relay emails to it after they've gone through Postsrsd. Change in /etc/postfix/master.cf Code: 127.0.0.1:10022 inet n - n - - smtpd ... -o content_filter=smtp: ... to Code: 127.0.0.1:10022 inet n - n - - smtpd ... -o content_filter=smtp:127.0.0.1:2525 ... and restart Postfix. Because we copied main.cf from Postfix' primary instance to the secondary instance all mysql hooks to ISPConfig settings are kept intact. Including relaying a domain to another host from within ISPConfig's settings! Only manual action left for a sysadmin is when you set a relay host for the entire host in ISPConfig. Find lines like these in /etc/postfix/main.cf: Code: relayhost = ... smtp_sasl_auth_enable = yes smtp_sasl_security_options = ... smtp_sasl_tls_security_options = ... smtp_sasl_password_maps = ... and copy to or replace them in /etc/postfix-relay/main.cf. [EDIT] I've automated this last manual step with a cronjob that runs a simple search&replace script every 5 minutes. See the comment below. This concludes the tutorials on how to install and implement Sender Rewriting Scheme in an ISPConfig Perfect Server.
If I'm not mistaking relayhost settings are available in ISPConfig's database. So when a mysql hook can be implemented in Postfix then it replaces the sysadmin manual action and all is automated directly from ISPConfig again. Same as sender relayhost already does.
I found that Postfix doesn't support mysql queries in relayhost. So I'll create a script to check for changes in relayhost settings in Postfix' primary instance and replicate it to the second instance to restore ISPConfig's function.
Made a quick (and probably dirty ) script that: searches for relevant relayhost lines in Postfix' primary instance main.cf searches for the same relevant relayhost lines in Postfix' secundary instance main.cf compares the lines from both replaces a line in Postfix' secundary instance main.cf with the line found in Postfix' primary instance if a difference between the two is found reloads Postfix, only if differences were found A cronjob runs the script every 5 minutes. The relevant relayhost lines to search for are put as strings in an array after which a loop does the search, compare and replacement if necessary for every string in the array.
Thanks a lot remkoh for your tutorial, I tried in my ISPconfig with Ubuntu 24.04 and it works as a charm ! So it is still up to date and I think ISPconfig team should integrate it in the core. The forward function would be useful for many people who want to forward mail to external address. So I followed the part 1 and part 2 as I I have a relayhost. It still work in 2026. The only trouble I have now is with Aws SES itself that I use as a relayhost. The message that I want to forward is rejected by Aws because postsrsd has rewrittent the return-path OK but not the sender address itself. So the domain and the user is not verified by aws of course ([email protected]) while forwarding and aws reject it. I need to rewrite the sender domain itself not only the return-path so the domain would be example.com. It would be good to provide a reply to with the gmail address. I tried to change the sender and the reply to in main.cf but it works for all email and I would like to be applied only with the forward emails rewritten by postsrsd. I would be very pleased if you give me a little help.
