Use the WebAdmin Interface to configure the IMAP module. Open the Access page in the Settings realm:
Use the Log setting to specify the type of information the IMAP module should put in the Server Log. Usually you should use the Major (message transfer reports) or Problems (message transfer and non-fatal errors) levels. But when you experience problems with the IMAP module, you may want to set the Log Level setting to Low-Level or All Info: in this case protocol-level or link-level details will be recorded in the System Log as well. When the problem is solved, set the Log Level setting to its regular value, otherwise your System Log files will grow in size very quickly.
The IMAP module records in the System Log are marked with the IMAP tag.
When you specify a non-zero value for the Maximum Number of Channels setting, the IMAP module creates a so-called "Listener". The module starts to accept all IMAP connections that mail clients establish in order to retrieve mail from your server. The setting is used to limit the number of simultaneous connections the IMAP module can accept. If there are too many incoming connections open, the module will reject new connections, and the mail client should retry later.
By default, the IMAP module Listener accepts clear text connections on the TCP port 143, and secure connections - on the TCP port 993. Follow the listener link to tune the IMAP Listener.
The IMAP module supports the STARTTLS command that allows client mailers to establish a connection in the clear text mode and then turn it into a secure connection.
Send 'Running' every: If this setting is not set to Never, the IMAP module monitors how long it take to execute the APPEND, COPY, and SEARCH operations. If any of these operations takes longer than the specified period of time, the module sends an "untagged" response to the client application. This feature can be used to prevent client application time-outs, and it can also help in dealing with various NAT boxes that tend to close connections if they show no activity.