Several readers have reported that the new release does indeed solve many of the issues introduced by the first iteration, with one small caveat:
IMAP re-build may be necessary MacFixIt reader Linc Davis reports that he had to re-build his Cyrus IMAP database per instructions contained in Knowledge Base document #107996 to get mail service properly working again.
"I was one of the casualties of the first 'Security Update' (no IMAP service.) The second version did not solve the problem immediately. I had to rebuild the IMAP database according to the procedure in the Knowledge Base article, and I had to temporarily move all Mail.app user files out of the way (~/Library/Mail and ~/Library/Preferences/com.apple.mail), then recreate the IMAP accounts, and finally restore the original files. I also had to restart SMTP (Postfix) at least once to get it working again. At the moment everything seems to be working, though I suspect I may have lost some messages.
"Note that there is an omission in the above-referenced Knowledge Base article: after renaming /var/imap, you have to create a new, empty directory with that name (mkdir /var/imap) before running mkimap.