From the idea of integrated the Email into openERP , is execelent , but now when it comes to practicality , 
We test and let you know our result ,
with our server , Xeon CPU , 2.4 GHz , 2GB Ram , where ONLY email account which
is set currently active using the incoming mail to pull into the message and with about 1 months 
of mails , 
from 1/Mar – 14,138 KB (14MB) to 23/Mar – 98,767KB (98MB)
And after login using this user which is set using this email account , the message page will take
few minutes before it can display properly and everytime after you click Archive the
message , it will load again and take around a few minutes ,
so Malaysia / Singapore SME ,  imagine if you are to set incoming email for more users and 
to FULLY use the messaging system without using email client anymore , 
on one hand ,it is good that you have all messages been backup properly , but when it comes
to retrieving or viewing the messages , in fact when it comes to backing up
the messages , the disk space you need to consider…  to me i do not think it is ready for production 
use yet ,
We have to resolve to other solutions but still continue to use this useful features of openERP ,
EMAIL SOLUTIONS for openERP is still remain NOT CLEAR at the moment, but believing 
it would evolve and we do have some wild idea but that is too big of a change … and we have
no resource for developing yet …
so do you want to take the risk of taking your own email servers and get it fully integrated with
openERP ?