I have the same problem, look the report: (its in spanish, but its the mail accounts part)
Cuentas de Correo
Servicio de correo On
Total 50
Acceso Panel Control 50
Buzones correo 50
Redirecciones 0
Grupos correo 0
Autorespondedores 0
Tamaño total 193 MB <----------- Total Size 193 MB
Tráfico 359 MB/Mes
Cuentas de Correo
Nombre Acceso Panel Control Buzón Redireccionar Grupo de correo Autorespondedor Cuota Tamaño:
aldoberg On On Off Off Off Ilimitado 0.19 MB
alejandrojacobi On On Off Off Off Ilimitado 0.47 MB
anaspreafico On On Off Off Off Ilimitado 0.00 MB
angelbusson On On Off Off Off Ilimitado 0.00 MB
angelglas On On Off Off Off Ilimitado 0.19 MB
arielizaguirre On On Off Off Off Ilimitado 0.18 MB
arobles On On Off Off Off Ilimitado 0.02 MB
carlospereyra On On Off Off Off Ilimitado 1.06 MB
carlossomer On On Off Off Off Ilimitado 1.64 MB
cesarbecker On On Off Off Off Ilimitado 0.00 MB
cristianscamurra On On Off Off Off Ilimitado 0.00 MB
edgardogotte On On Off Off Off Ilimitado 0.29 MB
eduardofolmer On On Off Off Off Ilimitado 0.01 MB
emmanuelre On On Off Off Off Ilimitado 0.00 MB
fernandogareis On On Off Off Off Ilimitado 0.00 MB
folmernogoya On On Off Off Off Ilimitado 0.00 MB
gestoria On On Off Off Off Ilimitado 0.48 MB
gustavoheinzenknecht On On Off Off Off Ilimitado 0.00 MB
hugoeberle On On Off Off Off Ilimitado 0.00 MB
info On On Off Off Off Ilimitado 0.00 MB
isidoromasset On On Off Off Off Ilimitado 3.31 MB
javierfolmer On On Off Off Off Ilimitado 0.11 MB
jorgeespindola On On Off Off Off Ilimitado 1.86 MB
josebujhamer On On Off Off Off Ilimitado 0.00 MB
josecedermaz On On Off Off Off Ilimitado 0.00 MB
juancarlosbernat On On Off Off Off Ilimitado 0.00 MB
juancarloscoassolo On On Off Off Off Ilimitado 0.00 MB
juancarloshardock On On Off Off Off Ilimitado 0.00 MB
juancarloswolf On On Off Off Off Ilimitado 0.00 MB
marcelopittavino On On Off Off Off Ilimitado 0.00 MB
marianofolmer On On Off Off Off Ilimitado 0.02 MB
marisaalvarez On On Off Off Off Ilimitado 0.00 MB
minuto On On Off Off Off Ilimitado 0.00 MB
nataliauhrich On On Off Off Off Ilimitado 0.00 MB
oscarfuchs On On Off Off Off Ilimitado 2.31 MB
pablofolmer On On Off Off Off Ilimitado 0.42 MB
pablolaguna On On Off Off Off Ilimitado 0.00 MB
paolabierig On On Off Off Off Ilimitado 0.12 MB
planes On On Off Off Off Ilimitado 2.16 MB
planrombo.empresas On On Off Off Off Ilimitado 0.00 MB
repuestos On On Off Off Off Ilimitado 0.25 MB
rubenglas On On Off Off Off Ilimitado 0.05 MB
sebastian On On Off Off Off Ilimitado 0.00 MB
sebastianfolmer On On Off Off Off Ilimitado 0.00 MB
sergiodreise On On Off Off Off Ilimitado 0.00 MB
sergiosommer On On Off Off Off Ilimitado 0.00 MB
sergiososa On On Off Off Off Ilimitado 0.00 MB
tallermaquinarias On On Off Off Off Ilimitado 0.00 MB
veronica On On Off Off Off Ilimitado 0.00 MB
walterspahn On On Off Off Off Ilimitado 0.00 MB
The total size detailed in the account list is 15.14 Mb, where are the 178 Mb added??