So -- I got myself into another predicament, and out -- and just wanted to post my trials here, since google produced no results.
Was doing a portupgrade (from the portaudit output, saying vpopmail 5.4.3 had a security vuln) -- so I portupgraded vpopmail -- started seeing this error in my log, since I have users use port 587 submission with TLS authentication to send mail (instead of SMTP)
Sep 9 04:56:13 tract vpopmail[63295]: vchkpw-submission: vpopmail user not found <a href="mailto:ANTISPAM_READACTED" target="_blank">ANTISPAM_READACTED</a>:69.162.28.205
So now -- I figured it was caused by my portupgrade (oh, I also had to restore my ~vpopmail/etc/vpopmail.mysql file after the portupgrade
so instead, I just modded toaster-watcher.conf to say version 5.4.6 for vpopmail; /usr/local/etc/services stop; then did a toaster_setup -s vpopmail; /usr/local/etc/services start
walla -- no more error.
Hope this helps someone some day <img src="images/smiley_icons/icon_wink.gif" border=0 alt="Wink">
Just for reference, there's no need to do a services start/stop when recompiling vpopmail.
In this case, there's no harm in not upgrading vpopmail dependencies (qmail, qmailadmin, courier-imap, and sqwebmail) but in general, doing so is a good idea.
Also, as you note, it's best to upgrade vpopmail by using toaster_setup.pl. It knows how had vpopmail configured, where the port system hasn't got a clue and is likely to configure it differently, often in a way that doesn't work as you'd expect.