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

Calculating dependencies ... done!
Dependency resolution took 1.56 s (backtrack: 0/20).

[ebuild  N     ] net-libs/libesmtp-1.1.0-r2:0/8::gentoo  USE="ssl threads -static-libs" 166 KiB
[ebuild  N     ] mail-mta/esmtp-1.2-r2::gentoo  125 KiB
[uninstall     ] mail-mta/nullmailer-2.2-r2::gentoo  USE="ssl -test" 
[blocks b      ] mail-mta/esmtp ("mail-mta/esmtp" is soft blocking mail-mta/nullmailer-2.2-r2)
[blocks b      ] mail-mta/nullmailer ("mail-mta/nullmailer" is soft blocking mail-mta/esmtp-1.2-r2)

Total: 2 packages (2 new, 1 uninstall), Size of downloads: 291 KiB
Conflict: 2 blocks (all satisfied)