When I send an email from a group mail box the email shows my email address as the sender on behalf of the group email address. I would like to hide my email and only show my name as the sender and have the respond to as the group email address rather than my email address. I am using Notes 6.5. Could you please advise if there is a way to set up my client to do this.
Have a look at the Team Mailbox template on OpenNTF which provides the functionality to be able to respond with a team/group email address instead of your own email address: http://www.openntf.org/internal/home.nsf/project.xsp?action=openDocument&documentId=8E156950C4FB032686257760006044D1
Your best bet is to switch to the ID file of the group account, your administrator should be able to set you up. Using the group ID and associated location doc will show only the information for the group ID.
If you aren't able to switch, you should be able to set the reply-to address, it won't hide the "sent by" information showing that you created the email, but it will show the group address as the "from" and when they click reply should fill in the correct reply to address. Honestly, it should be filling in the correct reply to address anyway, but people often manually re-add the sender when they reply preferring to deal with the existing contact instead of going back to the group.