As net send is old and not always supported, msg is a good alternative

msg /SERVER:[PC you want to send a message to] * “[message]”

use of /TIME:[seconds] changes the alert’s lifetime from default 60 seconds

use of /V provides a bit more info, but nothing to write home about, however adding /V /W will let you know the user clicked “OK” with a ” Message to session [] responded to by user”