MDaemon will DKIM-sign email from local accounts - it signs outgoing email from SMTP-authenticated sessions. MDaemon has a Content-Filter action that is supposed to identify other messages that can be DKIM-signed in the remote queue. CCSoftware has confirmed they were unable to make it work either - the MDaemon logs indicate the filter is identifying the outbound messages, tags them for DKIM-signing, but the messages are delivered without the signing.

What worked:

1) created 'Relay.Admin' user in MDaemon, with strong password '123qweRTY'

2) updated 'MDaemon' Exchange Send Connector to use authentication with the new 'Relay.Admin@gateway.dsinfinite.solutions' account

3a) configure DKIM

updated which domains get signed

4) created TXT DNS record with public key

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This file saved as: D:\Data\MDaemon\PEM\MDaemon\dns_readme.txt

DKIM selector record for DNS:
     MDaemon._domainkey.gateway.dsinfinite.solutions. IN TXT "v=DKIM1; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDCamWH+sEjErbygFzq2kdMtgxLUai1qC7iD6W3e8mF2W3CdtGxOB9ilswZ3BAbz5Pah8jVKuyCo3sjhNLyqt03TIVf0erCv78PYYO+gyut1s/yDD2LzLKz4GsaD+1xk+auNqgzEmlsaCpUHnL0GjggFNBd9mEDHT2q5rswxqK78wIDAQAB"

Important note: the above examples are using your primary domain of "gateway.dsinfinite.solutions".

You may need to setup similar records using different domain names if you want

to sign mail for any other domains you are hosting.

See RFC 6376 for additional parameters you can add to your selector data in DNS.
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