These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.69 s (backtrack: 8/20).

[ebuild  N     ] net-libs/courier-unicode-2.3.2:0/7::gentoo  643 KiB
[ebuild  N     ] net-mail/courier-common-3.3.0::gentoo  USE="gdbm -berkdb" 2387 KiB
[ebuild  N     ] net-libs/courier-authlib-0.72.4::gentoo  USE="gdbm pam sqlite -berkdb -debug -ldap -mysql -postgres -static-libs" 2237 KiB
[ebuild  N     ] net-mail/courier-imap-5.2.11-r2::gentoo  USE="gdbm ipv6 -berkdb -debug -gnutls (-selinux) -trashquota" 3339 KiB

Total: 4 packages (4 new), Size of downloads: 8606 KiB

WARNING: One or more updates/rebuilds have been skipped due to a dependency conflict:

net-libs/courier-unicode:0

  (net-libs/courier-unicode-2.6.0:0/10::gentoo, ebuild scheduled for merge) USE="" conflicts with
    <net-libs/courier-unicode-2.4:= required by (net-mail/courier-imap-5.2.11-r2:0/0::gentoo, ebuild scheduled for merge) USE="gdbm ipv6 -berkdb -debug -gnutls (-selinux) -trashquota"
    ^                         ^^^  


!!! The following update(s) have been skipped due to unsatisfied dependencies
!!! triggered by backtracking:

net-libs/courier-authlib:0