I use MT-Blacklist to block blog spam on my weblog, but lately it’s been difficult to keep up with all of the new spam sites. So I typically turn on comments and trackbacks for a couple of days after posting something significant and then turn them off again.
To quickly disable all comments and trackbacks in Movable Type, simply go to “Core Setup | Preferences | Archiving | IP Banning,” and enter a blank IP address (i.e. just click the “Add” button). All comments and trackbacks will be blocked. To tun comments/trackbacks back on, delete the blank address.