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 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 and is running RHEL/CentOS 7. Only mail from the 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 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 or are sent (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 […]

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