Steps for Email ID disk space usages update
1. Login to Plesk Panel
2. Click "Subscriptions"
3. Enter concernred domain name in the search box
4. Press [[ctrl]] + [[v]]
5. Click "on required domain name"
6. Click "Mail"
7. Search for require email id of which space usages you want to refresh
8. Click this checkbox left to required email id of which usages stats you want to update
9. Click "Refresh Usage Stats"
10. wait for a while and system shall shortly share you new usages of that mailbox.