topic Re: How to reject spoofed mail in Operating System - Linux

How to reject spoofed mail

Muralidharan_2 — Thu, 08 Apr 2004 00:34:15 GMT

Hi

I am using postfix as my SMTP server which is running in Redhat 8.0.I used most of the UCE features of postfix to stop spam mail and it is doing better job.But I want to stop spoofed mail completely coming to my server.

thanks
Muralidharan

Re: How to reject spoofed mail

U.SivaKumar_2 — Thu, 08 Apr 2004 01:51:55 GMT

Hi,

Enable reverse lookup for connecting clients in postfix. Note that you will have run DNS servers with reverse zones for your own clients to connect properly to postfix.

edit /etc/postfix/main.cf
smtpd_client_restrictions = reject_unknown_client

To prevent spammers sending mail to your server with your sender address as your domain name from internet -

1) block mails from internet having sender domain as your domain.

2) To relay mails for your valid roaming users , who will have sender domain as your domain use authenticated relaying.

regards,

U.SivaKumar

Re: How to reject spoofed mail

Steven E. Protter — Thu, 08 Apr 2004 09:11:49 GMT

You can also go aol ballistic.

aol refused to accept mail from addresses that do not have valid reverse lookup records. A recent survery on my private servers show 75% of the inbound spam fails this test.

The problem is you'll need to use a sendmail hack and I have yet to figure out how to implement it.

Here is a copy of the hack and my thread which got no answers on how to implement it.

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=450771

SEP

Re: How to reject spoofed mail

Muralidharan_2 — Fri, 09 Apr 2004 00:03:47 GMT

Hi

Please give clear configuration for blocking mails from internet which having sender domain as my domain address

Regards

Muralidharan

Re: How to reject spoofed mail

U.SivaKumar_2 — Fri, 09 Apr 2004 03:09:17 GMT

Hi,

Edit main.cf

smtpd_recipient_restrictions =
permit_mynetworks,
reject_unauth_destination
check_sender_access hash:/etc/postfix/sender

edit /etc/postfix/sender and put the below line

yourdomain.com DISCARD

#postmap /etc/postfix/sender

#postfix reload

regards,

U.SivaKumar