I don't know about Outlook Express... I don't use it since I don't particularly care for being at greatly elevated risk of spam, viruses, malware, and phishing attacks. However, you can have multiple reply to fields in Mozilla Thunderbird, so presumably it is possible.
But you, and your boss if he's using Outlook or Outlook Express, would be well advised to move to something else. Pretty much ANY email client that doesn't have Outlook in the name would be a be a big step up security wise. Even Windows Mail in Vista seems to be the product of some hard lessons learned by Microsoft, though it's still too early to tell just how well those lessons were learned.
I'm wondering if there is a way to have multiple reply to addresses in Outlook Express.
My boss wants me to email him all the emails I send out to clients so I put both the client and his email in the To field. However, when the client replies is there anyway that the reply email will automatically go to both my email and my boss' email addresses?
You can't rely on the client to hit "reply all" instead of just reply even if I ask them to in my email so it goes to both of us. I am only part-time so if I'm not here when the client responds, he will have to wait until I am in the office to forwad to to him. It'd just be easier if 2 email addresses could be put in the reply to field in the account options.
Thanks for your help.