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40 lines
1.9 KiB
Markdown
40 lines
1.9 KiB
Markdown
From [Wikipedia](https://en.wikipedia.org/wiki/Sender_Policy_Framework):
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> Sender Policy Framework (SPF) is a simple email-validation system designed to detect email spoofing by providing a mechanism to allow receiving mail exchangers to check that incoming mail from a domain comes from a host authorized by that domain's administrators. The list of authorized sending hosts for a domain is published in the Domain Name System (DNS) records for that domain in the form of a specially formatted TXT record. Email spam and phishing often use forged "from" addresses, so publishing and checking SPF records can be considered anti-spam techniques.
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To add a SPF record in your DNS, insert the following line in your DNS zone:
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; Check that MX is declared
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domain.com. IN MX 1 mail.domain.com.
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; Add SPF record
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domain.com. IN TXT "v=spf1 mx ~all"
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This enables the Softfail mode for SPF. It is a good setting for getting started and testing everything. After verification, you might want to change your SPF record to: `v=spf1 mx -all`, to enforce the policy!
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Increment DNS serial and reload configuration.
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## Backup MX, Secondary MX
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For whitelisting a IP-Address from the SPF test, you can create a config file(See [policyd-spf.conf](http://www.linuxcertif.com/man/5/policyd-spf.conf/)) and mount that file into `/etc/postfix-policyd-spf-python/policyd-spf.conf`
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**Example:**
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Create and edit a policyd-spf.conf file here `/<your Docker-Mailserver dir>/config/postfix-policyd-spf.conf`:
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```shell
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debugLevel = 1
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#0(only errors)-4(complete data received)
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skip_addresses = 127.0.0.0/8,::ffff:127.0.0.0/104,::1
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# Preferably use IP-Addresses for whitelist lookups:
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Whitelist = 192.168.0.0/31,192.168.1.0/30
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# Domain_Whitelist = mx1.mybackupmx.com,mx2.mybackupmx.com
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```
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Then add this line to `docker-compose.yml` below the `volumes:` section
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```yaml
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- ./config/postfix-policyd-spf.conf:/etc/postfix-policyd-spf-python/policyd-spf.conf
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``` |