Postfix, TLS and self-signed certificates

Self-signing certificate means that it is not issued by a publicly trusted certificate authority like Let's Encrypt. This means that the certificate will not be trusted by applications which just trust publicly issued certificates - i.e. most applications. That's why you get this validation error.

Suppress weird "authentication failure" log while using pam_ldap with ssh on CentOS 7

Dell MD1200 (6gb/s jbod enclosure) and 12 Gb/s drives

Can I kill apt.system.daily to fix the apt install command?

VMware vSphere: Change the IP that vSphere sees/reports without changing the IP configured in the guest OS

Active Directory: Can Admin user install application under user profile?

Using a Windows Server 2012 R2 Server as a PDC via remote location

Ansible version on Ubuntu 20.04 LTS doesn't seem latest after repository set up

Amazon SES compromised

Installing and configuring open source tools that are unmanaged, with command line access, in Amazon AWS

can use psql on localhost but not on the server fully qualified name [duplicate]

configure my linux as a router, how do enable port forwarding with nftables?

If $a+b+c = 3abc$ and $\frac17 \leq k \leq 7$ prove $ \frac1{ka+b}+\frac1{kb+c}+\frac1{kc+a} \leq \frac3{k+1} $