As group owner/moderator can I change a group member's email address?

I own and moderate 3 different groups of people who are not particularly computer literate. When someone changes their email address I can tell them how to change their group address themselves by going to 'edit membership' but they often have difficulty doing so. For some, it would be a lot simpler if they could tell me their new address and I could change it for them but there doesn't seem to be a mechanism for a moderator to do this. Can anyone advise whether this can be done and, if so, how?