Change Plesk Mailbox Quotas with the Correct Scope

Plesk mailbox quota limits the space a particular mailbox may occupy. It is different from the total subscription storage allowance and from a subscription’s permitted per-mailbox limit. Raising one value does not guarantee more physical disk space or permission to exceed the service plan.

Change one mailbox through Plesk

1. Open your verified HTTPS Plesk account, choose the correct subscription/domain and go to Mail or Email Addresses, depending on the view.
2. Select the exact email address and inspect its current mailbox size setting and usage.
3. Choose Another size if allowed, enter the intended value and confirm its unit. Keep it within the subscription’s permitted limit; contact the provider if a larger allocation is required.
4. Save with OK, reopen the address and confirm the saved value. Check total available storage as well as the mailbox limit.

Reducing a quota below existing usage is not a safe way to clean messages. Preserve needed mail and understand how over-quota delivery behaves before reducing limits. A changed setting does not recover messages already rejected or remove old content automatically.

Linux administrator command-line scope

These are illustrative Plesk-for-Linux templates for an authorized administrator, not commands for a normal shared-hosting user to run. Inspect the installed utility’s help and record the previous setting before a real change.

plesk bin mail --update user@example.com -mbox_quota 50M

This targets one mailbox. The following command changes the subscription’s per-mailbox quota limit; it should not be described as automatically resetting every existing mailbox’s individual quota to 100 MB:

plesk bin subscription_settings --update example.com -mbox_quota 100M

Subscription changes can interact with service-plan synchronization and permissions. Review the effective plan and mailbox settings rather than changing a whole subscription to fix one mailbox. A successful command exit is not proof that the intended mailbox can now receive a new message.

Verify delivery and other constraints

Check the displayed allocation and usage after saving, then perform an authorized harmless delivery test if the original issue was over-quota rejection. Inspect the exact error if it persists: total disk capacity, inode limits, suspension, routing or another provider’s quota can be separate causes. Do not delete customer mail or enlarge unrelated accounts as an unreviewed workaround.

References: Plesk mailbox size, mail utility and subscription quota scope.

Reviewed October 15, 2026. Command arguments passed inert parsing checks only; no Plesk quota, service plan, mailbox or production delivery was changed or tested.