Atomicorp

I cannot run rpm -e psa-atmail or yum downgrade psa-atmail (same results as initial server)

well, have you installed and enabled yum-allowdowngrade? And can you see the plugin being used when runnning yum?

I placed a second post after the quote that you reference.
I think that I made some progress and would like some help with my previous post if you have time.

I would delete those red marked files. But check the difference between plesk and plesk.repo file to get the right one. I just decided it by datetime of the file.
-rw-r--r-- 1 root root 510 Nov 12 2009 asl.repo
-rw-r--r-- 1 root root 1333 Jul 30 23:51 atomic.repo
-rw-r--r-- 1 root root 1178 Dec 30 2008 atomic.repo.backup10122009
-rw-r--r-- 1 root root 2245 Apr 26 07:26 CentOS-Base.repo
-rw-r--r-- 1 root root 626 Apr 26 07:26 CentOS-Media.repo
-rw-r--r-- 1 root root 9924 Sep 3 02:32 plesk
-rw-r--r-- 1 root root 250 Sep 22 09:13 plesk.repo
-rw-r--r-- 1 root root 1414 Dec 10 2009 test.txt

I do not want Plesk to update via the repo.
I prefer to use the Plesk Control Panel.
Should I remove the "plesk" file?

It's safe to leave those. BUT if you run yum update and there are new updates in plesk.repo then they get installed too. Or if you have set yum to autoupdate.
So disable the repo if you don't want to use it. You can enabled it if needed. If you don't want to use it anyway then I would delete it.

But before disabling/deleting it downgrade psa-atmail by answering Y at then update psa-atmail again.

downgrade completed:

Removed:
psa-atmail.noarch 1:1.04-3.el5.art

Installed:
psa-atmail.noarch 1:1.02-cos5.build95100504.12

# yum upgrade psa-atmail
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: mirror.usonyx.net
* atomic: www4.atomicorp.com
* base: mirror.usonyx.net
* extras: mirror.usonyx.net
* updates: centos.maulvi.net
Excluding Packages from Plesk Server Administrator
Finished
Setting up Upgrade Process
Resolving Dependencies
There are unfinished transactions remaining. You might consider running yum-complete-transaction first to finish them.
The program yum-complete-transaction is found in the yum-utils package.
--> Running transaction check
---> Package psa-atmail.noarch 1:1.04-3.el5.art set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

====================================================================================================================================================
Package Arch Version Repository Size
====================================================================================================================================================
Updating:
psa-atmail noarch 1:1.04-3.el5.art atomic 3.5 M

Transaction Summary
====================================================================================================================================================
Install 0 Package(s)
Upgrade 1 Package(s)

Total download size: 3.5 M
Is this ok [y/N]: ???

Won't this simply install the same problem again?

NOTE:
# yum --disablerepo=atomic install psa-atmail
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: mirror.usonyx.net
* base: mirror.usonyx.net
* extras: mirror.usonyx.net
* updates: centos.maulvi.net
Excluding Packages from Plesk Server Administrator
Finished
Setting up Install Process
Package 1:psa-atmail-1.02-cos5.build95100504.12.noarch already installed and latest version
Nothing to do

This command was run prior to upgrade command

answer yes and upgrade it to the latest version from atomic again.

done, but...
http://webmail.kembalivillas.com

is the atmail webmail option available within Plesk and checked and set in the domain also?

yes to both.

then...
set Mail preferences to horde on that domain.
worked.
then reset to atmail
seems OK now.
http://webmail.kembalivillas.com/

Now I am going to create a file (plesk.repo) on the other server; the first server discussed in this post and attempt to replicate these steps...

hmm, that a totally other problem than the you started with.
http://atmail.webmail.kembalivillas.com/
is reachable so it's working but try to set Horde and than back to Atmail and disable mail for the whole domain for one moment and enable it back again.

does /etc/apache2/conf.d/zzz_atmail_vhost.conf exists and what is teh content?

Sorry, I was editing my previous post when you replied.

Now I am going to create a file (plesk.repo) on the other server; the first server discussed in this post and attempt to replicate these steps...

well, looky here...
http://webmail.3dminime-figurines-bobbleheads.com
(the original server mentioned in this post)

I think everything is back to normal regarding this atmail problem.
Do I need to worry about this command
yum --disablerepo=atomic install psa-atmail
originally mentioned by Scott?

RE: disable plesk.repo
Simply change the line?
enabled=0

Do I need to worry about this command
yum --disablerepo=atomic install psa-atmail
originally mentioned by Scott?

NO

Simply change the line?
enabled=0

YES

Thank you for your time.

I still feel like I am swimming through mud (but with floaties on)

You're welcome.