Enhanced e-mail SPAM protection in ISPConfig 3

The command below enables a stricter SPAM handling for postfix on ISPConfig 3 servers. In Detail: Reject sender hostnames with invalid syntax Reject sender hostnames that are no fully qualified domains (e.g. reject "server1" but allow server1.domain.tld) Reject sender domains that have no DNS records Check sender IP addresses against realtime blacklists. First make a ... Read more

Send all outgoing email trough one IP address in postfix

When a server has more than one IP address, then postfix will use all IP addresses randomly to send out emails. This can cause your emails to be listed as SPAM on other servers because the sending IP does not match the reverse IP of the server hostname. The solution is to bind postfix to ... Read more

Fix for OpenSuSE error: postfix/master: fatal: Servname not supported for ai_socktype

You might see the error: postfix/master[5309]: fatal: Servname not supported for ai_socktype On a OpenSuSE server when you enable smtps in postfix master.cf file. The reason for the error is that the definition of the smtps port in /etc/services is missing. Solution Edit the /etc/services file vi /etc/services and add the following lines: smtps ... Read more

Manage the postfix mailqueue with postsuper, postqueue and mailq

Postfix provides with postsuper, postqueue and mailq some  shell utilitys to manage the mailqueue. Here are some examples for common tasks: List all messages that are in the mailqueue postqueue -p The output looks like this: [email protected]:/# postqueue -p -Queue ID- --Size-- ----Arrival Time---- -Sender/Recipient------- 501CA23B43DB     2182 Thu Dec  3 14:24:39  [email protected] (Host or domain ... Read more

How to enable port 465 (smtps) in postfix mailserver

More and more internet access providers are closing port 25 to reduce spam except for connections to their own mailservers. If you run your own mailserver and have problems to connect to it on port 25, you can enable port 465 (smtps) in postfix as a workaround. Edit the /etc/postfix/master.cf file: vi /etc/postfix/master.cf and remove ... Read more

Install postfix with MySQL support on CentOS 5.3 (64Bit)

The following article explains the steps to compile postfix MTA with MySQL support on CentOS 5.3 as e.g. needed for ISPConfig 3. Remove the postfix package from CentOS which does not has MySQL support: /etc/init.d/postfix stop rpm -e --nodeps postfix Download the postfix source RPM and install it: cd /tmp wget http://mirror.rackspace.com/CentOS/5.3/os/SRPMS/postfix-2.3.3-2.1.el5_2.src.rpm rpm -i postfix-2.3.3-2.1.el5_2.src.rpm ... Read more

Postfix: “queue file write error”

If you get an error like: Aug 21 12:41:03 webb4 postfix/sendmail[11234]: fatal: web1_user(12967): queue file write error in your mail log, then the vale for message_size_limit in postfix main.cf is too low. Edit postfix main.cf: vi /etc/postfix/main.cf and set the message size limit to a higher value. E.g. message_size_limit = 900000000 and restart postfix: /etc/init.d/postfix ... Read more