Deploy Simple-Login App Behind Caddy 2.3.0 using Docker Compose
First you need to generate a private and public key for DKIM:
openssl genrsa -out dkim.key 1024
openssl rsa -in dkim.key -pubout -out dkim.pub.key
We will need the files dkim.key and ``dkim.pub.key``` for the next steps.
For email gurus, we have chosen 1024 key length instead of 2048 for DNS simplicity as some registrars don't play well with long TXT record.
Please note that DNS changes could take up to 24 hours to propagate. In practice, it's a lot faster though (~1 minute or so in our test). In DNS setup, we usually use domain with a trailing dot (.) at the end to to force using absolute domain.
Create a MX Record that points example.com to app.example.com. with priority 10.
An A Record that points app.example.com. to your server IP. If you are using CloudFlare, please disable the Proxy option.
Set up DKIM by adding a TXT Record for dkim._domainkey.example.com. with the following value:
v=DKIM1; k=rsa; p=PUBLIC_KEY
with PUBLIC_KEY being your dkim.pub.key but
- Remove the
-----BEGIN PUBLIC KEY-----and-----END PUBLIC KEY----- - Join all the lines on a single line
For example, if your dkim.pub.key is
-----BEGIN PUBLIC KEY-----
ab
cd
ef
gh
-----END PUBLIC KEY-----
then the PUBLIC_KEY would be abcdefgh.
Similar to DKIM, setting up SPF is highly recommended. Add a TXT Record for example.com. with the value:
v=spf1 mx -all
Setting up DMARC is also recommended. Add a TXT Record for _dmarc.example.com. with the following value
v=DMARC1; p=quarantine; adkim=r; aspf=r
This is a relaxed DMARC policy. You can also use a more strict policy with v=DMARC1; p=reject; adkim=s; aspf=s value.