I nodes are the total number of files and directories a user owns, it is counted by totaling the number of owning files and directories such as email message. A single email message consumes 1 inode if there is no attachment. Every single file or directory occupies 1 inode on file system.
We have some resource usage limitations for DirectAdmin accounts that are in place to prevent abusive use of services. Please read the limitations of DirectAdmin hosting accounts here : Resource Limitations
Some users complain they do not host any high number of files in their accounts but still their inodes limit is reaching to the limits. If this is the case, you should check your email accounts for any old emails specially the primary account that starts with your username as described below:
Please watch below video to free up the inodes usage.
Let us know if you have any issues freeing up the inodes, or above method does not work for you.