Outlook Error Codes

How to Fix NDR Error 554 5.2.2 Mailbox Full in Outlook

Maira Mehtab Sep 22, 2026 869 views

Question details

The user needs to resolve a nondelivery report (NDR) returning an error code indicating the recipient's mailbox has reached its storage capacity.

Product: Microsoft Outlook / Exchange
Device & OS: not provided
Scenario: Sending an email to a recipient or a mail-enabled public folder within a Microsoft 365 environment.
Observed behavior: The sent email bounces back with a nondelivery report (NDR) containing error code 554 5.2.2, stating that the destination mailbox or public folder cannot accept more messages.

Before you start

Determine whether you are the sender receiving the bounce-back message or the administrator managing the recipient's mailbox, as senders cannot fix this issue directly and must rely on the recipient to clear space.

Solution 1Recommended

Clear Mailbox Space or Increase Quota (For Administrators and Recipients)

If you manage the affected Microsoft 365 account, you must reduce the mailbox size or have your IT administrator increase the storage quota.

This error is strictly a server-side storage issue. A Microsoft 365 administrator must intervene to check the storage quota limits of the recipient's mailbox or the mail-enabled public folder.

Contact your IT Administrator

If you are the recipient experiencing full storage, reach out to your Microsoft 365 business account administrator to report the issue.

Check mailbox quotas in the Exchange Admin Center

Administrators should log in to the Microsoft 365 Exchange Admin Center, locate the affected user or mail-enabled public folder, and review the current storage usage against the assigned quota.

Archive or delete old content

Instruct the user to permanently delete unnecessary emails, empty the Deleted Items folder, or move older messages to an In-Place Archive to immediately free up space.

Increase the storage limit

If the business subscription allows, the administrator can increase the mailbox quota limit for the user to restore email delivery functionality.

For Senders: If you are trying to send an email and receive this error, you cannot resolve it on your end. Try contacting the recipient via phone or instant messaging to inform them their mailbox is full.

Free Microsoft Office alternative

Try WPS Office for Seamless Document Management

While email delivery and mailbox quotas are managed through your email provider, you can streamline your everyday office tasks with WPS Office. It provides a lightweight, highly compatible, and free alternative to Microsoft Office for creating documents, spreadsheets, and presentations.

1. Download the software: Visit the official WPS Office website and download the free installation package for your operating system.
2. Install WPS Office: Run the downloaded installer and follow the simple on-screen instructions to set up the software.
3. Open your files: Launch WPS Office and directly open your existing Microsoft Office files without losing any formatting.

Free, lightweight, and fast to install.Fully compatible with Microsoft Word, Excel, and PowerPoint formats.Built-in PDF editing tools for comprehensive document management.Familiar user interface ensures a seamless transition.

microsoft office alternative - wps office

Frequently Asked Questions

What exactly does NDR Error 554 5.2.2 mean?

This error code indicates that the recipient's mailbox or the mail-enabled public folder has exceeded its storage quota and is currently unable to accept any new messages.

Can I fix the 554 5.2.2 error if I am the sender?

No, senders cannot fix this error because it is caused by the recipient's storage being full. You must contact the recipient through another method so they can clear space in their inbox.

Does emptying the Deleted Items folder help resolve this error?

Yes. For the recipient, permanently deleting items from the Deleted Items or Junk Email folders reduces the total mailbox size, which can quickly drop storage below the quota limit and restore email delivery.

Microsoft Office Error Codes