Postfix Mail Limits
September 14, 2008 Postfix Configuration
Managing Mail Limits
The main.cf file contains several settings to manage mail limits.
Limit Recipients
This parameter limits the number of recipients for a single message. The default is 1000 set in the smtpd_recipient_limit setting.
Message Size Limit
The message size is restricted to 10 MB by default. This is a setting that you will need to consider disk space and the needs of users. This is set in the message_size_limit parameter.
Error Protection
Postfix tracks errors or attacks from a client. To ensure the safety of the system Postfix increases a delay limit each time an error or an attack comes from a client. This error limit is found in the smtpd_error_sleep_time and has a default of 1 second. Postfix increases the delay by 1 second for each additional error after error reach the smtpd_soft_error_limit. The client is disconnected when the error count goes to the smtpd_hard_error_limit.
smtpd_error_sleep_time = 1s smtpd_soft_error_limit = 10 smtpd_hard_error_limit = 20
This example demonstrates that Postfix will increase delay 1 second after error reach 10 and then disconnect one error reach 20.
The mail size can be limited by placing a parameter into main.cf. The parameter is the message_size_limit = size
If you wanted to change from the default 10 M size maximum for mail you could add this line in the main.cf at the end of the file:
message_size_limt = 12
