I'd like to write a Domino servlet that will stamp outgoing mail with a DKIM domain keys signature. We would generate the Domino mail server DKIM signature and put it in a TXT file with the DNS manager. How can I stamp an outgoing message with the encryption key? We would then add the DKIM signature to the header prior to releasing from mail.box.
1 Answers
Although requested by many, HTC Domino doesn't yet support DKIM nor DMARC. Implementing DKIM on Domino might not be as easy as writing a little servlet, as it involves canonicalization, computing hashes and signing them. After that, you'd have to add a signature header that has a strict format.
Although it's all documented in the RFC 6376, many things can go wrong. Therefore, I wouldn't recommend trying to write an own implementation for DKIM signing. On the other hand, if you did that and got it working, there's indeed a huge demand for this feature! Frankly, because you are asking this question on such an abstract level, you aren't quite there yet.
A more suitable solution might be setting up another SMTP server in front of the Domino server and configuring it to trust & DKIM stamp mail from Domino. There are e.g. many tutorials on how to achieve this with Postfix & OpenDKIM.

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I would think I could implement openDKIM somehow so as not reinvent the wheel. I have written lots of Java mail and mime handling scripts. Canonicalization, computing hashes and singing are not difficult, just tedious. I don't want to put an SMTP server in front of the Domino server. I want a Domino solution, if I have to write it myself. ;-) – teleman May 09 '20 at 13:36