When disabling SSLv3 in Zimbra, setting zimbraMtaSmtpdTlsProtocols equal to !SSLv2, !SSLv3 is not enough by itself.
Use the following as well:
postconf -e smtpd_tls_protocols='!SSLv2,!SSLv3'
postconf -e smtpd_tls_mandatory_protocols='!SSLv2,!SSLv3'
Article ID: 196, Created: 4/28/2025 at 12:56 PM, Modified: 4/28/2025 at 12:56 PM