Postfix mail server limit the mailbox size

last updated in Categories Linux, Postfix, Tips, Troubleshooting, Tuning, UNIX

So how do you limit the mailbox size for users configured with the Postfix mail server?


It is good choice to avoid problem (disk DoS) by limiting mailbox size. This will avoid the user or hacker to eat up all hard disk space.

Display the default mailbox size limit

Type the following command:
# postconf mailbox_size_limit

mailbox_size_limit = 51200000

51200000 bytes is default mailbox size limit.

Display the default maximum size in bytes of a message

Type the following command:
# postconf message_size_limit

message_size_limit = 10240000

Setup new mailbozsize limit

Open file /etc/postfix/ and
# vi /etc/postfix/
Add/modify/set values as follows:
mailbox_size_limit = 30000000
message_size_limit = 10240000

Save and restart postfix mail server:
# /etc/init.d/postfix restart


Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

6 comment

    1. Hi, you have to use LDAP or Mysql so you may create an attribute that defines the mailQuotaSize for each user.
      In my site, I have a complete guide to do this, but is in spanish.

  1. My maths is a little rusty but I think that 3 is a smaller number than 5. In other words in effect you have shrunk the mailbox_size_limit. Perhaps adding a zero to 51200000 or just doubling the figure would do it.

    all the best

  2. Scrap that. I have just realised that the post is to shrink the mailbox size. Its just that yesterday I was looking to grow the mailbox size and got fixated upon that idea.

    all the best

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