452 SMTP bounce: insufficient storage

What 452 means

The receiving server has no room to store the message right now. The sender should retry later.

Message text

Requested action not taken: insufficient system storage

Common causes of 452

• Recipient server's disk or storage quota is full

How to fix 452

1. Retry later.
2. If the recipient is yours, free storage or raise the quota.
3. Send to fewer recipients per connection if the server limits transaction size.

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How to read 452

The first part, 452, is the SMTP reply code. Requested action not taken, insufficient system storage: the server has no room for the message right now. Replies that start with 4 are temporary and replies that start with 5 are permanent (RFC 5321 §4.2.1).

This reply carries no enhanced status code. The three-digit reply code is the only machine-readable signal, so read the text that follows it to learn the reason.

Sending servers should retry a deferred message. RFC 5321 §4.5.4.1 advises waiting at least 30 minutes between attempts and trying for at least 4 to 5 days before giving up and returning a bounce. If the deferral keeps repeating, fix the cause rather than waiting.

Official source: www.rfc-editor.org. Last verified 2026-10-20.

Related guides

• How to create an SPF record (syntax and examples)
• How DKIM works and how to publish a DKIM record
• How to set up a DMARC record, from p=none to p=reject

Related codes

• 421 SMTP: service not available
• 450 SMTP: mailbox unavailable
• 451 SMTP: local processing error
• 4.2.2 SMTP: mailbox full
• 4.4.1 SMTP: no answer from host
• 4.7.0 SMTP: security status

FAQ

All bounce codes