1)
Message message-GEANT_CA4.eml is signed by certificate provided by CA "GEANT Personal CA 4" / CESNET.
SOGo Web Mail shows "green label - Message is signed" for this message, but it shows empty information about used certificate.
When I save smime.p7s from this message and I run command for detail information about it (on the SOGo server), I get right output:

# cat smime.p7s | openssl pkcs7 -inform der -print_certs -noout

subject=postalCode = 160 00, O = "CESNET, z\C3\A1jmov\C3\A9 sdru\C5\BEen\C3\AD pr\C3\A1vnick\C3\BDch osob", street = 1903/4 Zikova, ST = "Praha, Hlavn\C3\AD m\C4\9Bsto", L = Praha, C = CZ, CN = Milo\C5\A1 Wimmer, emailAddress = wimmer@cesnet.cz
issuer=C = NL, O = GEANT Vereniging, CN = GEANT Personal CA 4
subject=C = NL, O = GEANT Vereniging, CN = GEANT Personal CA 4
issuer=C = US, ST = New Jersey, L = Jersey City, O = The USERTRUST Network, CN = USERTrust RSA Certification Authority

This happens for every certificate provided by "GEANT Personal CA 4" / CESNET .
Maybe SOGo has problem with characters with diacritics?

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2)
Message message-TERENA_CA3.eml is signed by certificate provided by CA "TERENA eScience Personal CA 3".
SOGo Web Mail shows detail information about used certificate right.

# cat smime.p7s | openssl pkcs7 -inform der -print_certs -noout
subject=C = NL, ST = Noord-Holland, L = Amsterdam, O = TERENA, CN = TERENA eScience Personal CA 3
issuer=C = US, O = DigiCert Inc, OU = www.digicert.com, CN = DigiCert Assured ID Root CA
subject=DC = org, DC = terena, DC = tcs, C = CZ, O = University of West Bohemia, CN = Milos Wimmer 17169@zcu.cz
issuer=C = NL, ST = Noord-Holland, L = Amsterdam, O = TERENA, CN = TERENA eScience Personal CA 3