
Step 1: Change directory to /var/log/

Step 2: Look for a file named mail.log

Step 3: Open it. Type cat mail.log
to open its content.

Another method to check its log and status:
sudo systemctl status postfix@-

Step 1: Change directory to /var/log/
Step 2: Look for a file named mail.log
Step 3: Open it. Type cat mail.log
to open its content.
sudo systemctl status postfix@-