Author Topic: Spam Filtering by Subject Line  (Read 1659 times)

0 Members and 1 Guest are viewing this topic.

Offline
*
Spam Filtering by Subject Line
« on: March 06, 2022, 10:49:19 AM »
Spammers are so intelligent and They are sending Spam with the following subject line :

your Dropbox has stopped syncing
Income Tax return 2021 issued
Please Check Your Identity Immediately
suspended incoming messages
Your Password is about to expire
Account Suspension Notice
Shipment has been completed
Advertise up to 200 MILLION EMAILS

If we block above subject by REJECT command , Spammer will get notification, Sometimes spammers has no return valid path . So we will DISCARD those email by the following settings :


Code: [Select]
# vi /etc/postfix/header_checks

/Bitcoin/                                                                    DISCARD
/Dropbox has stopped syncing/                          DISCARD
/Wetgeving/                                                               DISCARD
/Income Tax return 2021 issued/                                  DISCARD
/PSD2/                                                                         DISCARD
/Please Check Your Identity Immediately/                        DISCARD
/suspended incoming messages/                                     DISCARD
/Your Password is about to expire/                                  DISCARD
/Bescherm uw account/                                                  DISCARD
/Account Suspension Notice/                                          DISCARD
/Shipment has been completed/                                     DISCARD
/Advertise up to 200 MILLION EMAILS/                            DISCARD
/To:.*<>/                                                                     DISCARD
/From:.*<>/                                                                DISCARD
/^Subject:/                                                                 WARN
 

Code: [Select]
# postmap /etc/postfix/header_checks
# systemctl restart postfix

Offline
**
Re: Spam Filtering by Subject Line
« Reply #1 on: March 06, 2022, 02:58:21 PM »
I don't think spammers cares about the Reject status, because most of the times it's bots. Same for the greylisting. Most of them won't try again after a 4.x.x response.

So, greylisting (a bit aggressive for my taste) + spamassassin + spamhaus/blacklist checks = The best spam protection without false positives.

You can't have 100% spam protection without false positives.

Offline
*
Re: Spam Filtering by Subject Line
« Reply #2 on: March 07, 2022, 07:47:16 AM »
you are missing the important part of having that file included in the postfix conf to work

/etc/postfix/main.cf:
Code: [Select]
header_checks = pcre:/etc/postfix/header_checks
VPS & Dedicated server provider with included FREE Managed support for CWP.
http://www.studio4host.com/

*** Don't allow that your server or website is down, choose hosting provider with included expert managed support for your CWP.

Offline
*
Re: Spam Filtering by Subject Line
« Reply #3 on: March 07, 2022, 10:03:36 AM »
I don't think spammers cares about the Reject status, because most of the times it's bots. Same for the greylisting. Most of them won't try again after a 4.x.x response.

So, greylisting (a bit aggressive for my taste) + spamassassin + spamhaus/blacklist checks = The best spam protection without false positives.

You can't have 100% spam protection without false positives.
Hi,
does CWP have greylisting?
Is it possible to activate it?
I think that this should solve many of spam problems, I am currently facing.

Thx

Offline
**
Re: Spam Filtering by Subject Line
« Reply #4 on: March 07, 2022, 10:12:56 AM »
I don't think spammers cares about the Reject status, because most of the times it's bots. Same for the greylisting. Most of them won't try again after a 4.x.x response.

So, greylisting (a bit aggressive for my taste) + spamassassin + spamhaus/blacklist checks = The best spam protection without false positives.

You can't have 100% spam protection without false positives.
Hi,
does CWP have greylisting?
Is it possible to activate it?
I think that this should solve many of spam problems, I am currently facing.

Thx

You are going to need to manually install it.
https://wiki.centos.org/HowTos/postgrey?action=fullsearch&context=180&value=spf

Offline
*
Re: Spam Filtering by Subject Line
« Reply #5 on: June 26, 2022, 07:46:00 PM »
I don't think spammers cares about the Reject status, because most of the times it's bots. Same for the greylisting. Most of them won't try again after a 4.x.x response.

So, greylisting (a bit aggressive for my taste) + spamassassin + spamhaus/blacklist checks = The best spam protection without false positives.

You can't have 100% spam protection without false positives.
Hi,
does CWP have greylisting?
Is it possible to activate it?
I think that this should solve many of spam problems, I am currently facing.

Thx

You are going to need to manually install it.
https://wiki.centos.org/HowTos/postgrey?action=fullsearch&context=180&value=spf

Hi iraqiboy90,

When I add the desired settings to the postfix mail configuration. Will I have a problem with the CWP mail server structure?

When I add the following parameters to the current configuration settings, it gives an error in the logs. Is it possible for you to share your configuration structure?

/etc/postfix/main.cf

smtpd_recipient_restrictions =
    permit_mynetworks,
    reject_unauth_destination,
    check_policy_service unix:postgrey/socket,
    permit
« Last Edit: June 26, 2022, 07:48:04 PM by cantay »