lots of mailboxes with same names at different domains

[waterboy@]

Hello

Can somebody help me with the following:

i want to have about 150 mailboxes at 3 domains. it's like
human1@domain1.tld human2@domain1.tld human3@domain1.tld

human1@domain2.tld human2@domain2.tld human3@domain2.tld

human1@domain3.tld human2@domain3.tld human3@domain3.tld

ofcourse the part before the @ can be anything but it exists at the 3 domains

so if there is a box for john.baker it should be possible to mail to it at the 3 domains. i guess 2 of 3 will redirect to the first box.