> Source: [sk176729](https://support.checkpoint.com/results/sk/sk176729)

# sk176729 - MTA 'deferred' queue builds up and does not release emails

| Property | Value |
|----------|-------|
| Solution ID | sk176729 |
| Date Created | 2021-12-09 |
| Last Modified | 2022-11-23 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R81.20, R81.10 (EOS), R81 (EOS) |
| OS | Gaia |

## Symptoms

- * Emails are accumulating in the MTA "deferred" queue.
* Postfix queue shows many emails with this message:   
  `
  [Expert@HostName:0]# /opt/postfix/usr/sbin/postqueue -c /opt/postfix/etc/postfix/ -p
  `  

  `
  4HfWQQ6gfZzD5c9 79716 Wed Oct 27 10:31:21 bounce@domain.com (host 10.1.1.30[10.1.1.30] said: 452 4.3.1 Insufficient system resources (SystemMemory) (in reply to end of DATA command)) user@domain2.com 
  `

## Cause

Next Hop IP, which is usually an email server, sent this error: "`452 4.3.1 Insufficient system resources (SystemMemory)`".

## Solution

This solution requires authentication. Please log in to view the full solution.

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