This normally occurs due to ISP (Internet Service Provider) problems, but when you own your own server (locally or live) you haven’t got the luxury to complain and sit back, so here’s how to fix the problem on a Linux server.

The 452 error is normally associated to overloading the email queue; which usually likes to be at least 1.5x the size of:

message_size_limit

which can be specified in:

/etc/postfix/main.cf

Requirements

This how to, assumes you have command line access to your server, if you don’t and have this problem then contacting your ISP is probably the first port of call, if you have any queries don’t hesitate to give us a shout, we can normally respond within a few hours if we are not here.

Fixing Error 452 Insufficient storage space

1. From root type:
   cd /etc/postfix/

   Always make sure to make a backup before editing the original file, to make a backup of this file type:

   cp /etc/postfix/main.cf -R /etc/postfix/main_backup.cf

2. Then use vim to open the original cf file, type in:

   vi /etc/postfix/main.cf

3. This will open the required file, once in the file, search for the line message_size_limit entry, type (the forward slash / is paramount):

   /message_size_limit and hit the return or enter key

4. To begin editing the line, hit the letter “i” for insert:

   i

5. Use the cursor keys to navigate up and down. You may notice that the mail_box_size_limit is in close proximity to the message_size_limit this is useful because the latter obviously needs to be lower than the mail_box otherwise Postfix will crash.
6. We set the following:
   mailbox_size_limit = 150000000
   which roughly equates to 130Mb per mail box

   message_size_limit = 35000000
   which roughly equates to 32Mb per message

7. To exit insertion mode hit the
   Esc key
8. to save your changes to the opened file press
   SHIFT button, then ZZ keys
9. To restart Postfix, type
   /etc/init.d/postifx restart
10. Joy, you’ve now made the required changes
11. Well done, sit back and think you’ve just saved £150+ p/h that your ISP would’ve charged on your dedicated to solve the prob