mbox

For mbox, the mail separator is "From " in the beginning of lines. The incm utility does not convert ">From " to "From " in the beginning of lines in the body. On Solaris, Content-Length: should be used with the -c option to tell the end of mail.

To lock mbox, a lock file("<user>.lock"), flock() or lockf(), and open(O_EXLOCK) are used.

maildir

For maildir, no lock and no separator are necessary.

Consider the following situation:

        cur/{1,2}


        new/{3,4}

Executing incm without the options results in:

        cur/{1,2}


        new/{}


        to inbox: {3,4}

Executing incm with the -a option results in:

        cur/{}


        new/{}


        to inbox: {1,2,3,4}

Executing incm with the -b option results in:

        cur/{1,2,3,4}


        new/{}


        to inbox: {3,4}

Executing incm with the -a option and the -b option results in:

        cur/{1,2,3,4}


        new/{}


        to inbox: {1,2,3,4}