Nope. The issues with exchange I have seen usually are on the username. So assuming you are using 2007, the options for username can be:
domain\username <-- default option when Exchange is set up
username
username@domain.com
domain.com\username <-- sometimes people require the .com
domain\username:email@domain.com <-- odd, but possible
Also, it is possible that a username is different than the mailbox. For example on my test server I have an email address and a username that is very different. So my setup looks something like:
Email:
iron@maiden.com
username: maiden\bruce
password: *******
server: ip address, but it can also be something like XXX.XXX.com
port: 443
Secure: checked