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

Calculating dependencies ... done!
Dependency resolution took 0.99 s (backtrack: 0/20).

[ebuild  N     ] acct-group/popa3d-0-r2::gentoo  0 KiB
[ebuild  N     ] acct-user/popa3d-0-r2::gentoo  0 KiB
[ebuild  N     ] net-mail/popa3d-1.0.2-r2::gentoo  USE="maildir pam -mbox" 37 KiB

Total: 3 packages (3 new), Size of downloads: 37 KiB