First of all, i setuped mail system outside of VE, e.g. on VE0, on HN. And postal shows 800 mails per second  
  
So HN is powerfull enought but somehow don`t offer it`s power to VE!
Some testings:
inside of VE on "new HN":
# time bonnie++ -u root -s0 -f -n 256:1:1:2
Version  1.03       ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files:max:min        /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
          256:1:1/2  7607  63  1398   1 11012  20  9626  81  1296   1  2143   4
real    9m57.871s
user    0m1.287s
sys     0m57.784s
Outside of VE on "new HN":
#  time bonnie++ -u root -s0 -f -n 256:1:1:2
Version  1.03       ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files:max:min        /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
          256:1:1/2  4105  44  1076   0 10262  18  5391  59   842   0  2111   4
     
real    13m37.166s
user    0m0.653s
sys     1m11.004s