Moving mail from one server to another?

[Visco]

I'm in the process of moving a lot of my clients hosting packages onto my reseller account. I'm fine transferring all the necessary files to the new server, but I'm stuck when it comes to moving over existing mail on the old server to the new one.

Is there a specific location where the emails are stored on the Blacknight's Linux servers?

[blacknight]

Was the mail with on linux or windows previously?

[Visco]

The mail is on a Soho Linux package at the moment, and I need to transfer it over to a Reseller Linux server.