I ended up installing (which, btw, does not for a postgresql backend remove the ~postgres/data directory contents), setting the iRedMail repo to be a higher priority, and reinstalled (i had to modify get_all.sh to add an appropriate "priority=" line when creating the .repo). All good, now.

Of course, I would certainly prefer not to override redhat distributed packages if at all possible (especially since RedHat won't provide support for repackaged RPMs).

Seems there was also an issue with the amavis/clamav packages which came either from redhat or from epel.

Unfortunately, not. Unclear if an issue with RPM stuff or something screwy because I had selinux turned on when I did the intial install. I did a complete reinstall of iredmail using iredmail.repo with the highest priority and with selinux off, and all worked well.

Quite a few package overrides in iredmail, so being able to use the Redhat (or even epel) provided packages where possible would be a good thing.

Fair enough... do your rebuild the packages in the iRedMail repo for security updates/etc?

If you have a list of what packages Redhat is missing as well as a list of what packages Redhat provides but are either the wrong version or missing a piece or compiled with the wrong options, I can use my support contract with RedHat to file one or more RFEs against RHEL6.x .

I am having the same issue trying to install iRedMail on the default Amazon Web Services AMI.

How is this solved? What does "setting higher priority in iRedMail repo file" mean?

Transaction Check Error:
  file /usr/lib64/dovecot/settings/libmanagesieve_login_settings.so conflicts between attempted installs of dovecot-managesieve-2:0.2.6-21.el6.x86_64 and dovecot-pigeonhole-1:2.0.9-2.9.amzn1.x86_64
  file /usr/lib64/dovecot/settings/libmanagesieve_settings.so conflicts between attempted installs of dovecot-managesieve-2:0.2.6-21.el6.x86_64 and dovecot-pigeonhole-1:2.0.9-2.9.amzn1.x86_64
  file /usr/libexec/dovecot/managesieve conflicts between attempted installs of dovecot-managesieve-2:0.2.6-21.el6.x86_64 and dovecot-pigeonhole-1:2.0.9-2.9.amzn1.x86_64
  file /usr/libexec/dovecot/managesieve-login conflicts between attempted installs of dovecot-managesieve-2:0.2.6-21.el6.x86_64 and dovecot-pigeonhole-1:2.0.9-2.9.amzn1.x86_64

That was the first thing that I tried. I did:

sudo yum remove dovecot

Is there anything else necessary to remove?

I tried again to uninstall dovecot and then to install iRedMail and it's still giving the exact same errors. I will note that I am trying to install on the Amazon default AMI. I used instructions from here:
http://www.inboxs.com/index.php/linux-o … ail-on-ec2

to fake that the system is really "CentOS release 6.2 (Final)" so that it would install. However, do you think it is possible that there is a conflict?

When I do that it says that I'm only removing one package:

---> Package dovecot.x86_64 1:2.0.9-2.9.amzn1 will be erased
...
Removing:
 dovecot                             x86_64                             1:2.0.9-2.9.amzn1                               @amzn-main                             5.6 M
...

That's the package that I've tried removing already. Is it possible that I require a *different* version of dovecot?

I am somewhat new to this, so please excuse what might seem like a basic question, but: Is it possible to force yum to install a different version of yum - one that does not come from the "amaz-main" repository?

Thanks for you all your help with this.