Convert Addon Domain to Account faced a problem

Hello,

We have an hosting plan with unlimited disk space and two days before we move one account an limited hosting plan with low disk space. After moving it using the tool in WHM Convert Addon Domain to Account the account was moved but email account moving failed because of Disk quota exceeded the error message we have added below. What is problem is non of the email account in that domain names are not moved or create in the new hosting plan. As we check the user old hosting plan their emails was not there and in the new hosting plan. So is there any solution to recover it we don't know how to recover it or how to do it restore it using WHM So please help us on this it was making too much trouble and even we never know what are the email account that domain own before moving to an another hosting plan and we also need to know is there any back stored in the server if the process was stuck because of Disk quota exceeded in the server. So please help us to make an immediate action.

Error details showing in the View Conversion History tab details options added below

11. Copying webmail data

• The system failed to set the user ID to “1003” and the group ID to “1005” on “/home/domain/.sqmaildata” because of an error: No such file or directory

12. Copying FTP accounts

• The system failed to write to the file “/home/domain/etc/ftpquota.lock-5d8b-5a3d7d68-472a87d45d82” because of an error: Disk quota exceeded

14. Copying installed SSL certificate

• The system failed to write to the file “/home/domain/ssl/ssl.db.lock-5d8b-5a3d7d68-333517fa9ef18” because of an error: Disk quota exceeded

So please look and tell us an immediate solution..