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As documented by Postfix you can use the following two restrictions in smtpd_sender_restrictions in main.cf: reject_unlisted_sender Reject the request when the MAIL FROM address is not listed in the list of valid recipients for its domain class. See the smtpd_reject_unlisted_sender parameter description for details. This feature is available ...


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The answer was that I used public key in KeyFile instead of PrivateKey: KeyFile /etc/mail/dkim.key Changed to: KeyFile /etc/mail/dkim.private The problem is gone but DKIM signature is not shown on google side. There is not error log in mail.err every thing seems working on this side. I even digged TXT to see if DKIM ...


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Have you set the reverse dns of you domain? And are you sending the sender header in you email? As per me these two are required.


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Firstly, just for clarity on include, s5.2 of RFC 4408 says: Only the evaluated result of the referenced SPF record is used, rather than acting as if the referenced SPF record was literally included in the first. As to whether the MX RR in an included record refers to your MX, or the MX of the included domain, I cheerfully concede that OpenSPF's ...


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This is probably just https://en.wikipedia.org/wiki/Internet_background_noise , aka automated scripts looking for vulnerabilities of unpatched servers. You might want to setup a WAF like ModSecurity and have it IP-block suspicious requests. Patch your server regularly.


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Put the following line in your local.cf: report_safe 0 The spam information will still be available in the header, but it will not change the body of the email.


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Don't waste your time trying to find the source. It will be another victim. The spammer will have a network of compromised machines they are using. The first thing you should do is apply a password policy and force everyone to change their passwords. Make sure that you change the administrator password as well, as that is the most abused account. Next, on ...


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The correct solution to stopping backscatter without allowing harvesting of emails is to reject email for nonexistent users, but also use fail2ban to block directory harvesting attacks. So after the first few in a row from the ip it will get blocked. This gets the best of both worlds. By rejecting during SMTP, backscatter is prevented. By using fail2ban to ...



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