When a mail message arrives, qmail-local runs sh -c command in your home directory. It makes the message available on command's standard input.
WARNING: The mail message does not begin with qmail-local's usual Return-Path and Delivered-To lines.
Note that qmail-local uses the same file descriptor for every delivery in your .qmail file, so it is not safe for command to fork a child that reads the message in the background while the parent exits.
Currently 64, 65, 70, 76, 77, 78, and 112 are considered hard errors, and all other codes are considered soft errors, but command should avoid relying on this.
SENDER is the envelope sender address. NEWSENDER is the forwarding envelope sender address, as setup in dot-qmail(5). RECIPIENT is the envelope recipient address, local@domain. USER is user. HOME is your home directory, homedir. HOST is the domain part of the recipient address. LOCAL is the local part. EXT is the address extension, ext.
HOST2 is the portion of HOST preceding the last dot; HOST3 is the portion of HOST preceding the second-to-last dot; HOST4 is the portion of HOST preceding the third-to-last dot.
EXT2 is the portion of EXT following the first dash; EXT3 is the portion following the second dash; EXT4 is the portion following the third dash. DEFAULT is the portion corresponding to the default part of the .qmail-... file name; DEFAULT is not set if the file name does not end with default.
DTLINE and RPLINE are the usual Delivered-To and Return-Path lines, including newlines. UFLINE is the UUCP-style From_ line that qmail-local adds to mbox-format files.