[Dovecot] how to migrate from one server to another?

[Bram Mertens]

Hi

I have purchased and installed a new PC and would like to transfer my 
mail (in Maildir format) to it.

Are there any precautions I must take before copying the mail over?

I will disable mail delivery temporarily so no new mail gets written to 
disk but I don't know if dovecot has to be stopped before 
copying/editing mail for backup or migrating purposes.

Anything else I must pay attention to?

TIA

Bram