Using the stock php-imap-3.0.15-2 package from the Red Hat 6.2 Alpha
CD-ROM, I attempted to set up IMP, a web mail gateway package that uses
PHP3 to talk to an IMAP server. I used the RPMs horde-1.0.9-1, and
imp-2.0.9-1, available from http://www.horde.org/imp/. Although most
features of this package worked, it was impossible to delete messages.

The IMP faq describes a patch to php-3.0.15 that can fix this:
http://faq.horde.org/cache/192.html

It would be nice if Red Hat would release an updated php-imap-3.0.15-x
package with this patch, or alternately, if they would release a working
php-imap-3.0.16-x RPM. I tried using a Rawhide php-3.0.16-2.alpha.rpm and
php-imap-3.0.16-2.alpha.rpm package, but it appears that the IMAP module
does not actually get loaded into the PHP server. You can see whether the
IMAP module gets loaded by following these directions:
<http://faq.horde.org/cache/65.html>. I ran into the same problem when I
tried to roll my own php-3.0.16 RPM, so if the fix for this is to
just release a set of php-3.0.16 RPMS, you'll need to check whether the
IMAP module gets loaded, at least on the alpha architecture.

To get IMP to work and delete messages, I downgraded the PHP RPMs to
php-3.0.14-5 from one of the Rawhide distributions.