Categories

postfix

Biglobe is OP25B because there are regulations, to set via the relay server of Biglobe. Thus SASL to transmit authentication. SPF perform the source domain authentication in. S25R , Greylisting , Tarpitting prevent access from suspicious server approach. Because you do not want to do in the form of a patch to Postfix, the […]

Postfix With smtpd Access Restrictions

Anti-Spam Defense: Using Postfix With smtpd Access Restrictions

Fighting spam, aren’t we all… To stem the tide of unwanted junk mail look no further than the built-in access restrictions in Postfix.

If you find yourself the postmaster-in-chief, the last think you want is having to rely on your users to weed through spam and […]

Securing Your Postfix Mail Server with Greylisting, SPF, DKIM and DMARC and TLS

”Domain-based Message Authentication, Reporting & Conformance” (DMARC).

DMARC basically builds on top of two existing frameworks, Sender Policy Framework (SPF), and DomainKeys Identified Mail (DKIM).

SPF is used to define who can send mail for a specific domain, while DKIM signs the message. Both of these are pretty useful on their own, and reduce incoming […]

Postfix Implement SPF Record Checking

So I’ve been dealing with quite a bit of spam recently, the usual “You’re due a tax rebate open XYZ.zip and fill out the form”, etc. Following from my last blog post, Postfix Force SMTP Authentication, I noticed I never setup my mail server to check received mail against the senders SPF records, which I […]

Configuring Postfix as a Null Client

Configuring Postfix as a Null Client

This howto assumes that the relay server’s IP address is 192.168.1.22 and is running RHEL/CentOS 7. Only mail from the 192.168.1.0/24 network should be accepted and relayed.

Install Postfix [root@rhce-server ~]# yum install postfix

Configure Systemd [root@rhce-server ~]# systemctl enable postfix [root@rhce-server ~]# ^enable^start

Configure the Firewall [root@rhce-server ~]# […]

Quick postfix queue depth script

for i in `ls -al /var/spool/postfix |grep ‘^d’|awk ‘{print $9}’|grep -v ‘\.$’`; do c=`find $i|wc -l`; echo “$c $i”; done;

Postfix – whitelisting and spf filtering

Postfix – whitelisting and spf filtering

The whitelist will allow me to manually allow any mail servers to bypass the spf filtering and RBL(Real-time Blacklists) lists.

What does SPF filtering do? Suppose a spammer forges a Hotmail.com address and tries to spam you. They connect from somewhere other than Hotmail. When his message is sent, […]

Postfix – Blocking spam before it enters the server

Postfix – Blocking spam before it enters the server Posted in DNSBL E-mail E-mail spam Extended SMTP Mail transfer agents Postfix Spam filtering When i first setup the server part 1 and part 2 i used the basic setting for postfix but soon found that i could reduce the amount of spam and load on […]

Postfix Useful Commands

To Check Postfix Queue #mailq

To Check Sasl Auth #tail -f /var/log/messages|grep sasl

To Check Posfix Logs #tail -f /var/log/maillog|grep postfix

List of domains that are being deferred #qshape-maia -s deferred

Checking Specific Mail From Queue ————————————— To view the full mails #postcat -q D5EB71AEA45 If you an error postcat: fatal: open queue file D5EB71AEA45: […]

Specific Email Address From Your Mail Queue

You can check your current mail queue like this:

postqueue -p

To delete all mails from the mail queue that come from falko@example.com or are sent tofalko@example.com (the command is the same regardless of if it’s the sender or recipient address), you can use this command:

mailq | tail +2 | awk ‘BEGIN […]

Page 1 of 212