Note that eMule may save its configuration files in C:\ProgramData\eMule\config (this is the option “for all users”), instead of inside its own folder. You can change this at advanced settings > extended. eMule System Files:

Known.met: It saves all files which eMule knows for if they are shared, files currently in the download list or downloaded in the past. Information like file size, filename, hash sets, hash values and some statistics is saved for each and every file. If you delete this, eMule will have to rehash all files on the next restart.

Known2_64.met: Stores AICH hashes of all downloaded and / or shared files. If you delete this, eMule will have to rehash all files on the next restart.

Cancelled.met: All files which you cancelled before completing their download are noted here, so eMule can mark them to let you avoid redownloading them again.

Clients.met: It stores all users who have credits with your eMule.

Server.met: It contains all the known servers.

Emfriends.met: If users are added as your friends, they are stored in this file.

Preferences.ini: It saves all preferences that you set in the Options dialog, as well as information about visual details (column size etc). Some development related and advanced options can only be enabled by editing this file directly with a text editor.

Fileinfo.ini: Comments or Ratings for your own shared files.

Category.ini: Settings of your categories like name, comment and colour coding.

Ipfilter.dat: IP ranges and access levels to be filtered.

Onlinesig.dat: The server eMule is connected to – up / download statistics. Can be used by IRC scripts or signature images.

Preferences.dat: It keeps the user hash. This is a value calculated at eMule’s first start and is used to identify this client in the network. Used for credit system and friends.

Cryptkey.dat: It contains the unique 384 bit private RSA key of your client to verify your userhash. If you delete this file, make sure to also delete preferences.dat which stores your userhash.

Sharedir.dat: Holds the paths to all of your shared directories.

Staticservers.dat: Static servers never change their IP and are theoretically always online in the network. These servers can be added to staticservers.dat by the context menu (right mouse button) of the server list.

Addresses.dat: eMule updates its server list at startup if valid addresses to server.mets are provided in this file. Options -> Server offers a button to edit this list and the option for updating at start up. The file may contain multiply entries (one on each line) but only the first address to deliver a valid server.met is used.

AC_SearchStrings.dat: Each search string that has been used is recorded and an auto-completing is offered if a new search matches previous ones.

AC_ServerMetURLs.dat: Same file as the the one above. The only difference is that this one is used to store entered URL to server.met files. Mind that many sites regularly change the addresses to their server.mets.

Collectioncryptkey.dat: This file only exists if you have created and signed at least one collection in eMule. It contains a unique 1024 bit RSA key, which will be used for all collections you are signing to verify that they are from the same author.

eMule.tmpl: The *.tmpl files are required for the Webinterface. They define layout and options of the displayed pages.

xx.part: Part files are unfinished downloads. eMule is able to download from more than one user at the same time, so the *.part files always have the size of finished download. Missing parts are simply filled with zero. In recent versions, and when using the NTFS filesystem, you can enable the option to share incompleted files as ‘sparse’, which prevents this behaviour and saves disk space.

xx.part.met: Every *.part file has a corresponding *.part.met file. To identify a download in the network and to check for errors each download is divided to about 9 MB parts. For each part a so called hash value is calculated. Then a new hash value is created of the complete set of these part hashes. This information together with the file name and the status of the hashes are stored in the *.part.met files.

xx.part.met.BAK: A backup of the *.part.met files is created as it is very bad if such a file gets corrupted by a crash.

eMule.log: Saves the output of the Log window in the Server pane if the appropriate option in Options -> Extended is turned on

eMule_Debug.log: Saves the output of the Debug window in the Server pane if the appropriate option in Options -> Extended is turned on

src_index.dat, preferencesKad.dat, nodes.dat, key_index.dat, load_index.dat: They are used by Kad and contain infomation about known nodes, keywords, preferences etc.

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