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

Calculating dependencies ... done!
Dependency resolution took 1.65 s (backtrack: 0/20).

[ebuild  N     ] dev-db/lmdb-0.9.36:0/0.9.36::gentoo  USE="-static-libs" 147 KiB
[ebuild  N     ] dev-perl/Net-IP-1.260.0-r2::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 31 KiB
[ebuild  N     ] dev-perl/Digest-BubbleBabble-0.20.0-r3::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 45 KiB
[ebuild  N     ] dev-perl/Net-LibIDN2-1.20.0-r1::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 24 KiB
[ebuild  N     ] dev-perl/Net-DNS-1.560.0::gentoo  USE="-examples -minimal -test -verify-sig" PERL_FEATURES="ithreads (-debug) -quadmath" 260 KiB
[ebuild  N     ] dev-perl/Net-DNS-SEC-1.260.0::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 42 KiB
[ebuild  N     ] acct-group/polw-0-r2::gentoo  0 KiB
[ebuild  N     ] acct-group/postfix-0-r3::gentoo  0 KiB
[ebuild  N     ] acct-group/postdrop-0-r3::gentoo  0 KiB
[ebuild  N     ] acct-user/polw-0-r2::gentoo  0 KiB
[ebuild  N     ] acct-user/postfix-0-r3::gentoo  0 KiB
[ebuild  N     ] mail-mta/postfix-3.11.7::gentoo  USE="eai lmdb pam sqlite ssl -berkdb -cdb -dovecot-sasl -ldap -ldap-bind -mbox -memcached -mongodb -mysql -nis -postgres -sasl (-selinux) -tlsrpt -verify-sig" 5170 KiB
[uninstall     ] mail-mta/nullmailer-2.2-r2::gentoo  USE="ssl -test" 
[blocks b      ] mail-mta/postfix ("mail-mta/postfix" is soft blocking mail-mta/nullmailer-2.2-r2)
[blocks b      ] mail-mta/nullmailer ("mail-mta/nullmailer" is soft blocking mail-mta/postfix-3.11.7)
[ebuild  N     ] mail-filter/policyd-weight-0.1.15.2-r3::gentoo  81 KiB

Total: 13 packages (13 new, 1 uninstall), Size of downloads: 5797 KiB
Conflict: 2 blocks (all satisfied)