title: SSL_accept error in log while using Postfix
body: <p>So I set up a mail server on my VPS with cyberpanel and I can send emails manually through rainloop. I also have a program based on the lettre crate for Rust which runs perfectly fine on my own devices and correctly sends emails out through code. However when I try to run the program on my VPS, I get the following messages in my syslog.</p>
  <pre><code>globalfun postfix/smtps/smtpd[24656]: connect from localhost[::1]
  globalfun postfix/smtps/smtpd[24656]: SSL_accept error from localhost[::1]: -1
  globalfun postfix/smtps/smtpd[24656]: warning TLS library problem: error 14094418:SSL routines:ssl3_resl3_read_bytes: tlsv1 alert unknown ca:../ssl/rec/layer_s3.c:1543:SSL alert number 48:
  globalfun postfix/smtps/smtpd[24656]: lost connection after CONNECT from localhost[::1]
  globalfun postfix/smtps/smtpd[24656]: disconnect from localhost[::1] commands=0/0
  </code></pre>
  <p>I don't really understand why I can't send out emails through my program but it seems to have something to do with SSL. For reference, I have two servers on the same domain - one for my website which has an SSL installed through Let's Encrypt and another for the mail server which doesn't have SSL on it. That said, I don't think that's the issue as I can send emails through the mail server manually completely fine. Does anyone have any ideas as to what's wrong? Thanks in advance.</p>