Some mail wonkiness was happening, so I gave in and rebooted the server. Should be online shortly. 1336 CDT: Back up!
1436 CDT: Okay, not really sure why this would have caused issues, but … MailScanner was out-of-date, and it really started horking things up. I’ve upgraded it, and I’m presently upgrading ClamAV. I also updated the firewall. Mail that was appearing to have spooled is now starting to show up [for not only me but for other users]. Please holler if you have issues.