anebiiguanait.com
Date: Wed Dec 03 2008 - 03:40:45 CST

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> ------------------------------
>
> Date: Tue, 02 Dec 2008 14:50:21 +0100
> From: mouss <moussnetoyen.net>
> Subject: Re: Problems with backscaters and require authentication
>
> anebiiguanait.com a écrit :
> > Hi,
> >
> > i have some problems with spammers and i would like to ask how to set
> > postfix to validate sender email addresses only for our domains. Is
> > there some way to do this?
>
> what do you mean exactly by "validate"? check that the address exists?
> you can use reject_unlisted_sender.
>
> >
> > Other thing that i want to ask. I have this problem:
> >
> > i connect thru telnet to the smtp server and send email this way:
> >
> > helo myhostname.example.com
> > mail from:realusermydomain.com
> > rcpt to:realusermydomain.com
> > data
> > something here
> > .
> > quit
> >
> > mydomain.com is domain from the system.
> >
> > i'm able to send spam to this user, using the same email address in
> > "mail from" field.
> >
> > Is there some way to protect my mailserver from this kind of things for
> > our domains. If "mail from" use our domains (for example
> > usernamemydomain.com), then to require authentication.
> >
>
>
> smtpd_sender_login_maps =
> hash:/etc/postfix/sender_login
>
> smtpd_sender_restrictions =
> reject_sender_login_mismatch
>
>
> http://www.postfix.org/postconf.5.html#smtpd_sender_login_maps
>
>

Hi, thanks for the reply. Yes i mean to check if sender exists, but only
for our domains, not for all senders, because there are mail servers
that reject this kind of checking.

I suppose that when i configure this way my system, it will not make
problems with rest of senders, right?

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