I've said in a post before, that one email account has the same name as an actual user on the server. Obviously the mail user would be much easier to modify. Should I do this?
That depends on the email address and how you want to use it. If you dont want to use the user part in front of the @ for other mailboxes, then there has nothing to be changed. Changing the mail user might not always be an option e.g. if the system user that we talk about has the name "support", then it is not usefull to change all email users to a different name, instead you would change the system user. If the system user is e.g. firstname.lastname and you want to get all emails for firstname.lastname@... to this mailbox, then you can leave it as it is.