[exim] address rewriting: change name in "NAME" <domain.com>

Hi,

I use fetchmail, procmail and spamassassin to fetch and process mail on my
machine. I don't have a domain, but am connected via cable. While processing
mail, I sometimes need to send an email. I configured exim as smarthost with
address rewriting to change the From address.

The address rewriting works and emails reach their destination, but the From
address that is seen by the recipient contains the username of the local user
on my host.

The rewriting rule in exim.conf is:
   *@nowhere.com  ${lookup{$1}lsearch{/etc/email-addresses}\
                  {$value}fail} frFs

/etc/email-addresses contains:
root: thehog@???

Still, the email received appears to be sent by "root <thehog@???". Most
email clients thus show "root" as the sender (instead of "thehog").

How do I change the "root" into something different?

Thanks for your time,

theHog.