For some reason, MT stopped sending me any notifications of new comments posted here: annoying, that.
I never figured out why, but I worked around it. The docs say that you can use your host machine’s sendmail daemon or install the Mail::SendMail perl module and use another mail server. I chose that and use my cable modem/ISP’s mail server and all seems well now.
I did the usual tests (sendmail -bv www, cat /etc/hosts | mail www ) and they always worked (www is the username that should get all the comments): it’s assigned to a different address in /etc/aliases that seems to work just fine.