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Re: Relay mails from unknow networks/doma ins to a service provider for a r├ęcipient of m y domain.

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  • Michael Tokarev
    ... First, Don t accept mail from outside on your postfix server - for anything but your ISP s mailservers. And second, don t name your mail host
    Message 1 of 6 , May 31, 2006
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      Huby franck wrote:
      > Hi list,
      > I encountered this problem :
      > Some spam is sent to the recipients of our domain directly through our
      > postfix server (by smtp).
      > Actually the MX's of our domain are directed to the servers of a
      > provider that purge spam and viruses from mail sent to our domain's
      > recipients.
      > We have a postfix server for serving mail into our domain and for
      > outgoing mail.
      > Every mail sent to *@... will be relayed by the server of a
      > provider not by our postfix server even else for our internal users.
      > relaying of our provider is made through our postfix server.
      > Sometimes spam is sent directly via our postfix server and do not relay
      > by our provider (in the dns MX).
      > Is there a possibility to redirect (or relaying) mails sent directly (by
      > smtp from external unknow network) to our postfix server and to an user
      > of our domain to the server of our provider (who will relay or not
      > depends of spam/viruses contains) and keep our internal and outgoing
      > mail through our postfix ?

      First, Don't accept mail "from outside" on your postfix server - for anything
      but your ISP's mailservers.

      And second, don't name your mail host 'mail.yourdomain.tld' - something like
      smarthost, or smtp, or relay will be better (IMHO ofcourse).

      The thing is: some spammers are so stupid/lazy to a level when they don't
      want (or can't?) write a program to perform a DNS query.. And just tries
      to lookup an IP address of mail.$targetdomain. In your case it succeeds.

      And 3rd. Don't expose mail.yourdomain.tld anywhere in email addresses --
      set myorigin in postfix to yourdomain.tld (w/o the mail. prefix).

      > By advance thanks to all
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