Originally Posted by Matthew
There would be extra costs if the company was large (like the one I work for with 60k employees using MS Exchange), but it would look totally weird and random for all 60k employees to be using GMail or Yahoo mail addresses and certainly would be frowned upon by our clients who would think we were a bunch of muppets. Also, transmitting emails from a free account would also be frowned up on due to security policies with in the business which require emails to be encrypted in some cases.
So yes, there can be costs running your own email but on a per person basis I doubt it exceeds a few dollars a month at the most as you pointed out Blue. If our business chose to go the free email route then the results could cost more in losses due to clients "moving on" thinking we were not professional.
I'll grant you that in a very large company there will be added expenses for email. In the case of the company I work for with roughly 400 employees and11000 email users the cost is in operating our own email servers etc.
But the OP was in regards to web hosting companies using third party email.
This is never a case where I would find an acceptable reason for using hotmail etc.
Even if it is to add redundancy to your support system a host can always get an account off site for the purpose of backup email.