I could probably put together an 'finit' control messages for
/mail/fs/ctl that does the same thing.  Also, here's a patch for the
manpage, as well as one that removes /bin/seemail:

diff -r e05e4b6c6546 rc/bin/seemail
--- a/rc/bin/seemail	Mon Oct 12 02:03:52 2020 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,4 +0,0 @@
-#!/bin/rc
-
-if(~ $1 -i) exec faces -hi
-if not exec faces -h




diff -r e05e4b6c6546 sys/man/1/faces
--- a/sys/man/1/faces	Mon Oct 12 02:03:52 2020 +0200
+++ b/sys/man/1/faces	Fri Oct 16 20:06:45 2020 -0500
@@ -1,124 +1,77 @@
 .TH FACES 1
 .SH NAME
-faces, seemail, vwhois \-  mailbox interface
+faces, vwhois \-  notification interface
 .SH SYNOPSIS
 .B faces
-[
-.B -ih
-] [
-.B -m
-.I maildir
-]
-.br
-.B seemail
-.br
+
 .B vwhois
 .I person
 \&...
 .SH DESCRIPTION
 The
 .I faces
-command monitors incoming mail and
-displays in its window a representation of the user's mail box
-using a small image for each message.
+command monitors /mnt/plumb/notify and
+displays faces in its window for each well-formed message recieved
+on this port.
 The image is typically a portrait of the sender. Which image to 
-display is determined by two directories /usr/$user/lib/face 
-and /lib/face. Entries in /usr/$user/lib/face take priority over 
-those in /lib/face. See 
+display is determined by the `sender' and `facedir' attributes
+in the plumb message, with facedir defaulting to /lib/face. Entries in 
+/usr/$user/lib/face take priority over those in facedir. See 
 .IR face (6),
 for how these directories are organised.
-.PP
-If the user is running
-.IR plumber (4),
-.I faces
-reacts to plumb messages to the
-.B seemail
-port,
-typically from
-.BR upas/fs ,
-and is thus notified of message additions and deletions.
+Additionally, the `sender' attribute can optionally be formatted as follows:
+.EX
+	sender@site
+.EE
+This allows further control over which face is shown.
 .PP
 Right-clicking on a message icon causes that message to be `plumbed' to
-.BR showmail .
-A typical plumb action will be to display the message, such as by
-the rule
+the destination port specified in the original plumbing message, in the 
+`dst' attribute.
+Usually, the original generating application is listening on this port,
+but if it is not, a plumbing rule can be specified like
 .EX
     plumb start window mail -s $0
 .EE
-The
-.IR acme (1)
-mail reader listens to the
-.B showmail
-port automatically.
+If not specified, the message is plumbed back to the `none' port.
+All of the attributes specified in the original message are preserved; faces
+simply ignores extraneous ones. The `wdir' field in the original message is
+preserved similarly.
+Programs can also sent a `winid' attribute.  Faces will make the
+window with that id current.
 .PP
-If the user is not running
-.IR plumber ,
-.I faces
-reads the log file
-.F /sys/log/mail
-and right-clicking has no effect.
+An optional attribute is a `date' \- this is used to provide a more
+accurate timestamp. If unset, faces will use the date it received the
+notification, potentially differing from the date of the event that
+generated the notification.
+.PP
+The `data' field of the plumbing message should be something unique that
+allows the originating application to distinguish between notifications.
+It is sent back to the application unaltered when the face is clicked
+as the resulting plumbing message's `data' field.
+The `digest' attribute should be a hash of the `data' field concatenated
+with the application's name, to prevent hash collisions between
+applications that might be using the same hash algorithm and similar
+contents of `data' .
 .PP
 If arrows are visible, clicking on them will scroll the display.
 Middle-clicking on the arrows scrolls to the end.
 .PP
-Starting
-.B faces
-with the
-.B -i
-flag causes
-.B faces
-to read the messages in
-.BR /mail/fs/mbox
-— or the mailboxes specified with the
-.B -m
-flag —
-upon startup.
-.PP
-The
-.B -m
-option directs
-.I faces
-to watch for messages arriving in
-.I maildir
-instead of
-.BR /mail/fs/mbox .
-Multiple
-.B -m
-flags may be used to watch multiple mailboxes.
-.PP
-The
-.B -h
-flag causes a different, venerable behavior in which
-the window displays the history of messages received
-rather than the current state of the mail box.
-In particular, faces are not removed from the screen when messages are deleted.
-Also, in this mode clicking button 1 in the display will clear the window.
-.PP
-.I Seemail
-is an
-.IR rc (1)
-script that invokes
-.B faces
-.BR -h .
-.PP
 .I Vwhois
 tells
 .I faces
 to display the icons of the named
-.IR persons ,
-without sending a message.
+.IR persons .
 .SH FILES
-.BR /mail/fs/mbox   "   mail directory.
+.BR /mnt/plumb/notify   "   the destination port for notifications.
 .SH SOURCE
 .B /sys/src/cmd/faces
 .br
-.B /rc/bin/seemail
-.br
 .B /rc/bin/vwhois
 .SH "SEE ALSO"
-.IR mail (1),
-.IR marshal (1),
-.IR nedmail (1),
 .IR plumber (4),
 .IR face (6),
 .IR plumb (6)
+.SH BUGS
+There is no -i option anymore; instead, programs that wish to re-send old
+notifications should provide their own options to do so.