how can i follow different naming strategy for my exhcange enviornment

dear all,

Dont laugh after reading this need ur advice 😉

i have one domain wid one.com and our users using mails user@one.com but some users want to use accounts wid different domain name also like user@two.com,user@three.com same time user@one.com in there pcs and we have only one domain naming structure thats enough for us…so like these they just want to use these two and three mail accounts for to send mails and recieve mails.so how can i configure this in my exchange server 2003 is there any option for that ?
cna u advice me what to do?