server1:~# openssl s_client -starttls smtp -CApath /etc/postfix/certs/ -connect localhost:25
CONNECTED(00000003)
depth=0 /C=DE/ST=Sachsen-Anhalt/L=Dessau/O=ARTdomains/OU=Hosting/CN=mail.server1.art-domains.de/emailAddress=hostmaster@art-domains.de
verify error:num=20:unable to get local issuer certificate
verify return:1
depth=0 /C=DE/ST=Sachsen-Anhalt/L=Dessau/O=ARTdomains/OU=Hosting/CN=mail.server1.art-domains.de/emailAddress=hostmaster@art-domains.de
verify error:num=26:unsupported certificate purpose
verify return:1
depth=0 /C=DE/ST=Sachsen-Anhalt/L=Dessau/O=ARTdomains/OU=Hosting/CN=mail.server1.art-domains.de/emailAddress=hostmaster@art-domains.de
verify error:num=21:unable to verify the first certificate
verify return:1
---
Certificate chain
 0 s:/C=DE/ST=Sachsen-Anhalt/L=Dessau/O=ARTdomains/OU=Hosting/CN=mail.server1.art-domains.de/emailAddress=hostmaster@art-domains.de
   i:/C=DE/ST=Sachsen-Anhalt/L=Dessau/O=ARTdomains/OU=Hosting/CN=mail.server1.art-domains.de/emailAddress=hostmaster@art-domains.de
---
Server certificate
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
subject=/C=DE/ST=Sachsen-Anhalt/L=Dessau/O=ARTdomains/OU=Hosting/CN=mail.server1.art-domains.de/emailAddress=hostmaster@art-domains.de
issuer=/C=DE/ST=Sachsen-Anhalt/L=Dessau/O=ARTdomains/OU=Hosting/CN=mail.server1.art-domains.de/emailAddress=hostmaster@art-domains.de
---
No client certificate CA names sent
---
SSL handshake has read 1750 bytes and written 342 bytes
---
New, TLSv1/SSLv3, Cipher is EDH-RSA-DES-CBC3-SHA
Server public key is 1024 bit
SSL-Session:
    Protocol  : TLSv1
    Cipher    : EDH-RSA-DES-CBC3-SHA
    Session-ID: FEE6F8E6C38A6785D5BA0E14AE2E96CF751A5C6C05628855CC80B15453B6CC35
    Session-ID-ctx:
    Master-Key: 2765A994BC1B85ED7EE30E9975FD048FD29F6B669FDE1D4CDB248D90093C6B628D98E5B680643B9EC5B7B14A2E9FE4FF
    Key-Arg   : None
    Start Time: 1120147249
    Timeout   : 300 (sec)
    Verify return code: 21 (unable to verify the first certificate)
---
220 server1.art-domains.de ESMTP AMaVis-Postfix
quit
221 2.0.0 Bye
read:errno=0
server1:~#