What has changed in the certificate? Does the new certificate specify different algorithms, perhaps implicitly?

That is an OpenSSL error, complaining either that it does not like multipart/alternative or that the MIME type crypto/asn1 is not recognized. Perhaps you need a newer version of OpenSSL?

In reply to Re: Error reading S/MIME message with openssl by jcb
in thread Error reading S/MIME message with openssl by Anonymous Monk

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