70-236 - TS: Exchange Server 2007, Configuring

admin

to All MCSE!!!
please answer my question iam a new network admin in our company and preparing to take the exam of mcse we have a old network admin in this company but the problem our exchange server not inbound the mail from external email ( yahoo and aol. ect) inshort not working .my question like this it is the server 2003 standard are not working good with exchange server due to front end and back server are not supported? i decided to change the standard to enterprises . please support this answer