If have scripted sndfle.bat to allow you to NET SEND the contents of a text file to users. The syntax is:

sndfle filename \[User1 | /DOMAIN\] \[User2 User3 ... UserN\]

where:

Filename is the name of the text file, either single or multi-line, that contains the message text.

Userx is a list of usernames, separated by a space, who should receive the message. You may use /DOMAIN, instead of any usernames, to send to all users in the domain.

Note: The longest message I was able to send was 887 character to users and 127 characters to /DOMAIN.

sndfle.bat contains:

<b>
@echo off
setlocal
if \{%2\}<h1><a name="_echo_usage_sndfle_msgfile_user_list_amp_goto_end_if_not_exist_1_echo_usage_sndfle_msgfile_user_list_amp_goto_end_for_f_Tokens_i_in_type_1_do_call_setmsg_##_i_##_set_msg_msg_##_set_msg_msg_##_LOOP_if_2_">\{\} (echo usage: sndfle msgfile user-list) & (goto end)
if not exist %1 (echo usage: sndfle msgfile user-list) & (goto end)
for /f "Tokens=*" %%i in ('type %1') do call :setmsg ##"%%i"##
set msg=%msg:##"=%
set msg=%msg:"##=%
:LOOP
    if \{%2\}</a></h1>\{\} endlocal&goto end
    net send %2 %msg%
    shift /2
goto :LOOP
:setmsg
if not defined msg set msg=%1&goto end
set msg=%msg%%1
:end</b>