Massive /tmp files

Hello, I just found user who has single folder (standard maildir format) that filled with over 8mil files and 800GB in the /tmp subdirectory of that folder:

/email/domain/username/.Folder/tmp

The files in there are normal maildir email files.

I think the dir ran out of inode space so its not ongoing problem. My question is only can I purge that folder without breaking something more? If it tries to re-fill again I will try to debug

Thankyou!!