To disable TLSv1.0 and TLSv1.1 please follow these steps:

1. Make sure you have installed IMSVA Patch 3 build 1960 or a higher version.

2. Login to IMSVA via SSH or CLI using your root credentials.

3. Create a backup of the main.cf located in the /opt/trend/imss/postfix/etc/postfix/ folder.

4. Edit the main.cf file by appending !TLSv1, !TLSv1.1 at the end of the following parameters:

smtpd_tls_protocols
smtp_tls_protocols
smtpd_tls_mandatory_protocols
smtp_tls_mandatory_protocols

Example on how it will look like:

...
#smtpd_tls_protocols = !SSLv2, !SSLv3
smtpd_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
#smtp_tls_protocols = !SSLv2, !SSLv3
smtp_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
...
#smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
#smtp_tls_mandatory_protocols = !SSLv2, !SSLv3
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
...

5. Reload the postfix configuration by running:

postfix reload

6. Check whether the change took effect by running the following commands:

postconf | grep smtpd_tls_

postconf | grep smtp_tls_