tags 944513 moreinfo thanks A web search for the OpenSSL error message produces a few results, eg: https://sourceforge.net/p/opendkim/bugs/120/. Looks like a configuration issue. The error message is not particularly helpful, but that would be best directed upstream.
We would need more info on the config and setup steps. I’ve been using Postfix in a chroot with OpenDKIM listening on a Unix domain socket with no trouble. Cheers,