A full mailbox can reject new messages, stop syncing properly, and create confusing send and receive failures on connected devices.
Common symptoms
- Senders receive mailbox full bounces
- The user cannot receive new mail
- Mail apps sync inconsistently
Troubleshooting steps
- Log into webmail and check the mailbox usage or quota details.
- Delete unnecessary messages and empty spam and trash folders, which still consume space until purged.
- Archive older mail locally or to another mailbox if long-term retention is needed.
- Increase the mailbox quota if your hosting plan and mailbox policy allow it.
- After cleanup, test new inbound and outbound messages.
Additional notes
- Large sent, spam, and trash folders are common hidden storage consumers.
- One oversized mailbox can also affect backup size and sync performance.
When to contact support
Contact support if the mailbox shows free space but still reports quota problems.