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

Calculating dependencies ... done!
Dependency resolution took 1.03 s (backtrack: 0/20).

[ebuild  N     ] mail-filter/libmilter-1.0.2_p5:0/1.0.2_p5::gentoo  USE="-poll -verify-sig" 2317 KiB
[ebuild  N     ] acct-group/opendkim-0-r3::gentoo  0 KiB
[ebuild  N     ] acct-user/opendkim-0-r3::gentoo  0 KiB
[ebuild  N     ] mail-filter/opendkim-2.10.3-r32::gentoo  USE="ssl -berkdb -ldap -lmdb -lua -memcached -opendbx -poll -querycache -sasl (-selinux) -static-libs -stats -test -unbound" LUA_SINGLE_TARGET="lua5-1" 1182 KiB

Total: 4 packages (4 new), Size of downloads: 3499 KiB