Postfix SMTP server: errors from

I'm running the Postfix mail server ru000397.widhost.net. I'm getting some of these messages in [email protected].

The mail service is working and, obviously, there is much free space on all drivers.

Transcript of session follows.

 Out: 220 ru000397.widhost.net ESMTP Postfix
 In:  EHLO m145.gem.godaddy.com
 Out: 250-ru000397.widhost.net
 Out: 250-PIPELINING
 Out: 250-SIZE 52428800
 Out: 250-ETRN
 Out: 250-STARTTLS
 Out: 250-AUTH CRAM-MD5 DIGEST-MD5 LOGIN PLAIN
 Out: 250-ENHANCEDSTATUSCODES
 Out: 250-8BITMIME
 Out: 250 DSN
 In:  MAIL FROM:<[email protected]> BODY=8BITMIME
 Out: 452 4.3.1 Insufficient system storage
 In:  RCPT TO:<[email protected]>
 Out: 503 5.5.1 Error: need MAIL command
 In:  DATA
 Out: 503 5.5.1 Error: need RCPT command
 In:  QUIT
 Out: 221 2.0.0 Bye


For other details, see the local mail logfile

main.cf: http://pastebin.com/RCBx891e master.cf: http://pastebin.com/1HMyXzuT

Here is my df outputs:

[root@ru000397 ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2        22G   20G  1.5G  94% /
tmpfs           7.8G   12K  7.8G   1% /dev/shm
/dev/sdb        2.7T  1.7T  867G  67% /usr/local/psa

[root@ru000397 ~]# df -i
Filesystem        Inodes    IUsed     IFree IUse% Mounted on
/dev/sda2        1455328   242748   1212580   17% /
tmpfs            2035051        2   2035049    1% /dev/shm
/dev/sdb       181141504 11000662 170140842    7% /usr/local/psa

Here is my message_size_limit:

[root@ru000397 ~]# postconf -n|grep message_size_limit
message_size_limit = 52428800