Moved to WebFaction, configuring Exchange

Hello,

I am moving a client from another host to WebFaction.

I am ready to point his domain to the WebFaction DNS, but before I do this, we want to make sure his company's e-mail exchange server transitions smoothly.

I personally don't have any experience with exchange (assume that's MicroSoft Exchange?).

On WebFaction, I've setup all the same e-mail addresses and provided the client with mailbox names, passwords and e-mail server info (and link to WebFaction e-mail docs).

With that said, my client asked:

So as I understand it our current email exchange host will not change, just our passwords?

Which, I'm 99% positive that's yes to both above questions.

Does our exchange host need the new password info or is it just a change on our iPhones/thunderbird password settings etc?

I'm not sure how to answer that question.

Any tips on how to best migrate if someone has an "exchange" server setup? Do they just need to update the exchange server and then all devices will stay functional without any password changing? Does exchange act as a middle man between devices and the email server?

Any help, tips would be appreciated.

I will be sending the client a link to this question so he can listen to the conversation.

Many thanks in advance!