======Settings -> Diagnostics======
The **Diagnostics** page allows you to enable, configure and disable various methods of diagnostic logging, within VPOP3.

=====Log file overview=====
By default, VPOP3 will keep two copies of most log files:

  * The current log file, with a **.log** filename extension; which will be written to, until it reaches its maximum size. //e.g. vpop3.log//
  * The most recent old log file, with a **.lbk** filename extension; which was created from the previous **.log** file, when it reached its maximum size. //e.g. vpop3.lbk//

Where the settings are changed, causing additional old copies of the log to be retained, all older archives are renamed in the following way:
  * When a new **.lbk** file is created (as a consequence of there being a new **.log** file), the current **.lbk** file is renamed, so that the filename contains the current date and a sequential number (to allow multiple files per day). It is possible, for example, that the following logfiles would all exist simultaneously: 
    * //vpop3.log//
    * //vpop3.lbk//
    * //vpop3_20120101_1.lbk//
    * //vpop3_20111231_100.lbk//
    * //vpop3_20111231_99.lbk//

=====Tabs=====
====General====
The **General** tab allows you to specify the directory where VPOP3 will store the log files, change settings for the main VPOP3 log file, and preview some important log files.

**Log Path**<nowiki>*</nowiki>: Since version 5, the default location is the //**_logs**// folder, within the VPOP3 directory. //e.g. C:\VPOP3\_logs//\\
**Log Level**: How much is logged into the main diagnostic file, //vpop3.log// (Setting this to **Full Logging** may cause VPOP3 to run more slowly, but this is rarely noticeable).\\
**Maximum log size**: How large (in kilobytes) //vpop3.log// will be allowed to grow, before it is archived as //vpop3.lbk//

There are also buttons to preview various log files:
  * **View Main VPOP3 diagnostics Log** - //vpop3.log//
  * **View Error Log** - //errors.log//
  * **View Security Log** - //security.log//
  * **View Download Rules Log** - //dlrules.log//
  * **View MAIL.LOG** - //mail.log//
  * **View Connection Log** - //connect.log//
  * **View SMTP Rules Log** - //smtprules.log//
  * **View Virus Scanner Log** - //viruscan.log//

* //This setting does not affect certain log files, such as **exceptions.log**, which VPOP3 writes to when there is a significant performance issue, or a crash is imminent. To save time, and therefore increase the likelihood of VPOP3 being able to record the event, it will only look for **exceptions.log** in the root of the VPOP3 directory.//

====Session Logs====
The **Session Logs** tab allows you to administer logging of VPOP3's various services, along with its actions when it takes on the role of a client.

**Maximum log size**: Allows you to change the size of the session **.log** files, before they are archived into a **.lbk**.

===VPOP3 Service Logs===
  * **Log POP3 Server Connections** (Connections between POP3 email client and VPOP3) - //pop3svr.log//
  * **Log SMTP Server Connections** (incoming SMTP or connections between email client and VPOP3) - //smtpsvr.log//
  * **Log IMAP4 Server Connections** (Connections between IMAP4 email client and VPOP3) - //imapsvr.log//
  * **Log NNTP Server Connections** (Connections between Newsreader and VPOP3) - //nntpsvr.log//


===VPOP3 Connector Logs===
  * **Log POP3 Client Connections** (Connections between ISP and VPOP3) - //pop3clt.log//
  * **Log SMTP Client Connections** (Connections between VPOP3 and ISP) - //smtpclt.log//
  * **Log NNTP Client Connections** (Connections between VPOP3 and remote Usenet server) - //nntpclt.log//

====Temporary/Archived Files====
The **Temporary/Archived Files** tab allows you to enable a specific kind of logging, that is rarely (but occasionally) applicable in recent versions of VPOP3.\\
Because the files are now of very limited use, we do not recommend enabling these options, unless our Support team have specifically told you to do so.

When these settings are enabled, VPOP3 will rename certain redundant files, instead of deleting them, so they can be inspected afterwards.

There are three checkboxes:
  * **Keep Temporary Files** (Rename files to D*.DAT instead of deleting them)
  * **Automatically delete Temporary Files after** [-] **days** - //sets a maximum time for retaining old files, to limit the storage of old data//
  * **Archive Error Files** - //retain files that may contain important diagnostic information, related to an error//

There are two buttons, which will remove all retained temporary and error files:
  * **Delete All Temporary Files Now**
  * **Delete All Archive Files Now**


====Log File Sizes====
The **Log File Sizes** tab allows you to control the maximum size of various types of log file, and how long the files are kept.

===How long to keep OLD log files===
  * **Keep** [-] **old log files** - //The number of **.lbk** files to keep for each type of log - this is the default setting, and usually requires less disk space, but on a busy server, some log files will only cover a few seconds before filling up//
  * **Keep old log files for** [-] **days** - //The length of time to keep old log files - this can result in lots of files being stored, but should ensure you have time to inspect an issue, before the logs are overwritten//


===OLD Log file disk usage===
  * **Use no more than** [-] **MB for old log files (*.LBK)** - //This setting limits the amount of disk space taken up by old log files//
  * **Delete old log files (*.LBK) if less than** [-] **MB free disk space** - //This setting prevents VPOP3 from completely filling up a disk with old log files. When this threshold is reached, VPOP3 will begin removing old log files, to free up more disk space//

**//Note//**: Despite these settings, VPOP3 will not delete any **.log** file, or the most recent **.lbk** file.

===Maximum file sizes===
It is possible to set the maximum file size, for the following logs:

^Description  ^Filename(s)  ^Default size (kB)  ^
|Main Log File  |vpop3.log  |1024  |
|Main Error Log File  |errors.log  |1024  |
|Session Log Files  |pop3svr.log, smtpsvr.log, imapsvr.log, nntpsvr.log, pop3clt.log, smtpclt.log, nntpclt.log  |1024  |
|Download Rules Log  |dlrules.log  |100  |
|SMTP Rules Log  |smtprules.log  |100  |
|Security Log  |security.log  |100  |
|Virus Scanner Log  |viruscan.log  |100  |
|External Router Log  |extrouter.log  |100  |
|HTTP Client Log  |httplog.txt  |100  |
|AV Update Log  |avupdate.log  |100  |
|SMTP Transcript Log  |smtptranscript.log  |100  |
|POP3 Transcript Log  |pop3transcript.log  |100  |
|Lua Errors Log  |luaerrors.log  |100  |
|Instant Messaging Log  |vpop3_im.log  |1024  |
|Spam Rules Log  |spamrules.log  |1024  |
|Webmail Access Log  |webmail.log  |100  |