By default, it's kept in your MH directory. The log shows when you typed inc as well as scan lines for each message that's incorporated. To get more information, you can use a scan format file with inc . There are a few standard files or you can make your own format file to log just the information you want. For example, here's a line of the audit file made by the standard scan.time format file.
Most users use inbox as a place to sort out new mail and, often, to refile it to other folders.
If you want inc to drop the new mail into another folder, you have two choices. If there is one, inc uses that folder instead of inbox . That's because, like most MH commands, inc gets all the arguments from both the MH profile and the command line. If you have that problem, try using shell aliases for inc . Although these features may not be used as often as others, they can be handy.