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Updated Configure DKIM (markdown)

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Jean-Denis Vauguet 2020-05-31 05:10:32 +02:00
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docs/content/config/best-practices/dkim.md
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@ -1,19 +1,26 @@
To enable DKIM signature, you must have created your mail accounts.
Once its done, just run from inside the directory of docker-compose.yml:
DKIM is a security measure targeting email spoofing. It is greatly recommended one activates it.
See https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail for more details on DKIM.
## Enabling DKIM signature
To enable DKIM signature, you must have created at least one email accounts.
Once its done, just run the following command to generate the signature (here show from inside the directory of docker-compose.yml in order to use a volume on ./config):
docker run --rm \
-v "$(pwd)/config":/tmp/docker-mailserver \
-ti tvial/docker-mailserver:latest generate-dkim-config
The default keysize is 2048 for now. If you need to change it (e.g. your DNS-Provider limits the size) provide the size as the first parameter of the command
> The default keysize when generating the signature is 2048 bits for now. If you need to change it (e.g. your DNS-Provider limits the size), then provide the size as the first parameter of the command:
>
> docker run --rm \
> -v "$(pwd)/config":/tmp/docker-mailserver \
> -ti tvial/docker-mailserver:latest generate-dkim-config 2048
docker run --rm \
-v "$(pwd)/config":/tmp/docker-mailserver \
-ti tvial/docker-mailserver:latest generate-dkim-config 2048
Now the keys are generated, you can configure your DNS server with DKIM signature, simply by adding a TXT record.
Now the keys are generated, you can configure your DNS server by just pasting the content of `config/opendkim/keys/domain.tld/mail.txt` in your `domain.tld.hosts` zone.
After generating DKIM keys you should restart the app.
If you have direct access to your DNS zone file, then it's only a matter of pasting the content of `config/opendkim/keys/domain.tld/mail.txt` in your `domain.tld.hosts` zone.
```
; OpenDKIM
@ -22,7 +29,8 @@ mail._domainkey IN TXT ( "v=DKIM1; k=rsa; "
```
## Configuration using a web interface:
<details>
<summary>Configuration using a web interface</summary>
1. Generate a new record of the type `TXT`.
2. Paste `mail._domainkey` the `Name` txt field.
@ -30,19 +38,24 @@ mail._domainkey IN TXT ( "v=DKIM1; k=rsa; "
4. In `TTL` (time to live): Time span in seconds. How long the DNS server should cache the `TXT` record.
5. Save.
Note: Sometimes the key in `config/opendkim/keys/domain.tld/mail.txt` can be on multiple lines, if so then you need to concatenate the values
</details>
After generating DKIM keys, you should restart the mail server. DNS edits may take a few minutes to hours to propagate.
Note: Sometimes the key in `config/opendkim/keys/domain.tld/mail.txt` can be on multiple lines. If so then you need to concatenate the values in the TXT record:
```
; OpenDKIM
mail._domainkey IN TXT ( "v=DKIM1; k=rsa; "
"p=AZERTYUIOPQSDF..."
"asdfQWERTYUIOPQSDF..." ) ; ----- DKIM key mail for domain.tld
```
the target (or value) field must then have all the parts together `v=DKIM1; k=rsa; p=AZERTYUIOPQSDF...asdfQWERTYUIOPQSDF...`
the target (or value) field must then have all the parts together: `v=DKIM1; k=rsa; p=AZERTYUIOPQSDF...asdfQWERTYUIOPQSDF...`
## Verify-only
If you want DKIM to only verify incoming emails, the following version of /etc/opendkim.conf may be useful (right now there is no easy mechanism for installing it other than forking the repo):
If you want DKIM to only _verify_ incoming emails, the following version of /etc/opendkim.conf may be useful (right now there is no easy mechanism for installing it other than forking the repo):
```
# This is a simple config file verifying messages only
@ -97,9 +110,9 @@ mail._domainkey.domain.tld. 3600 IN TXT "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBA
```
## Switch off DKIM
Simply remove dkim key by recreating the mailserver-container.
Simply remove the DKIM key by recreating (not just relaunching) the mailserver container.
## DMARC
DMARC Guide: https://github.com/internetstandards/toolbox-wiki/blob/master/DMARC-how-to.md
DMARC Guide: https://github.com/internetstandards/toolbox-wiki/blob/master/DMARC-how-to.md