Ho To Disable ssl3 in OSX Server (for mail and Web hosting)
Depends on the Server...

Apache:
SSLProtocol All -SSLv2 -SSLv3

NGINX:
ssl_protocols TLSv1 TLSv1.1 TLSv1.2;

Postfix:
smtpd_tls_mandatory_protocols=!SSLv2,!SSLv3

Sendmail (sendmail.mc):
LOCAL_CONFIG
O CipherList=HIGH
O ServerSSLOptions=+SSL_OP_NO_SSLv2 +SSL_OP_NO_SSLv3 +SSL_OP_CIPHER_SERVER_PREFERENCE
O ClientSSLOptions=+SSL_OP_NO_SSLv2 +SSL_OP_NO_SSLv3

Dovecot (In /etc/dovecot/local.conf or /etc/dovecot/conf.d):
ssl_protocols = !SSLv2 !SSLv3

If you use virtual Servers with SSL, please note that you have to do this on all instances!