|/Addons||Addon scripts and utilities|
|/Bin||hMailServer binaries. The actual server and hMailAdmin|
|/Data||E-mail messages. The files in the Data root are messages that have not been delivered yet. Sub folders contain delivered messages. E-mail messages have the extension .hma or .eml, depending on in which hMailServer version they were created.
|/DBScripts||SQL scripts that are used when upgrading from one version to another. The files have the following naming standard: UpgradeXXXXtoYYYYZZZZ.sql. XXXX is the old version, YYYY is the new version and ZZZZ is the type of database server.|
|/Languages||Tranlations of the hMailServer user interface.|
|/Logs||Log files created by hMailServer.|
|/MySQL||The MySQL server|
|/PHPWebAdmin||The PHP web administration interface for hMailServer.|
|/Temp||Temporary directory used by hMailServer. For example used when hMailServer extracts attachments that needs to be virus scanned. When hMailServer extracts an attachment for virus scanning, it is given the extension .tmp.