relocating mail server

[tphan@iqrinc.com]

Hi,

  I'd like to setup my debian box to do mail server after I 
  mirrored the potato and installation.

  I'd like to know how to forward all the emails from my current
  email server to this new potato box?

  Here is the current setup:

     ISP <---- email ----> current mail server(hamm)

  I would like to setup:

     ISP <---- email ----> current mail server(hamm)
                                              ----> tobe new mail server(potato)
  So I do not have to call the isp to switch back and forth
  before I actually move the mail server.

  Thanks!

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tcp