(Past correspondence memo) I get the following error:
Out: 452 4.3.1 Insufficient system storage
Did you fail to receive mail due to insufficient free space on the mail server side? Looking at the SMTP error messages, there are the following two types. ： 452 4.3.1 Insufficient system storage ： warning: not enough free space in mail queue: 157245440 bytes < 1.5*message size limit
The area of / var is tight and is more than 1.5 times the value of message_size_limit set in main.cf. It looks like / var is running low on free space and mail delivery is failing.
# grep limit /etc/postfix/main.cf message_size_limit = 104857600
104857600 * 1.5 (message_size_limit) is larger than 157245440 (free / var at this point). I expanded / var for the time being and recovered.